[fix] buildprocess of docs in LXC (containers)

The $DOCS_BUILD variable (like all BUILD variables) in the lxc environment::

   sudo -H ./utils/lxc.sh cmd searx-archlinux make docs

is different from running build process in the HOST::

   make docs

with kernel-include directive we can use the environment variables in the reST
documents to address the correct file location of the include.

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

docs/admin/buildhosts.rst

@@ -21,13 +21,13 @@ on build hosts (see :ref:`searx.sh`).::
 
 This will install packages needed by searx:
 
-.. include:: ../../build/docs/includes/searx.rst
+.. kernel-include:: $DOCS_BUILD/includes/searx.rst
    :start-after: START distro-packages
    :end-before: END distro-packages
 
 and packages needed to build docuemtation and run tests:
 
-.. include:: ../../build/docs/includes/searx.rst
+.. kernel-include:: $DOCS_BUILD/includes/searx.rst
    :start-after: START build-packages
    :end-before: END build-packages
 

docs/admin/installation-searx.rst

@@ -17,7 +17,7 @@ universe repository.
 Install packages
 ================
 
-.. include:: ../../build/docs/includes/searx.rst
+.. kernel-include:: $DOCS_BUILD/includes/searx.rst
    :start-after: START distro-packages
    :end-before: END distro-packages
 
@@ -30,7 +30,7 @@ Install packages
 Create user
 ===========
 
-.. include:: ../../build/docs/includes/searx.rst
+.. kernel-include:: $DOCS_BUILD/includes/searx.rst
    :start-after: START create user
    :end-before: END create user
 
@@ -41,13 +41,13 @@ install searx & dependencies
 
 Start a interactive shell from new created user and clone searx:
 
-.. include:: ../../build/docs/includes/searx.rst
+.. kernel-include:: $DOCS_BUILD/includes/searx.rst
    :start-after: START clone searx
    :end-before: END clone searx
 
 In the same shell create *virtualenv*:
 
-.. include:: ../../build/docs/includes/searx.rst
+.. kernel-include:: $DOCS_BUILD/includes/searx.rst
    :start-after: START create virtualenv
    :end-before: END create virtualenv
 
@@ -55,7 +55,7 @@ To install searx's dependencies, exit the searx *bash* session you opened above
 and restart a new.  Before install, first check if your *virualenv* was sourced
 from the login (*~/.profile*):
 
-.. include:: ../../build/docs/includes/searx.rst
+.. kernel-include:: $DOCS_BUILD/includes/searx.rst
    :start-after: START manage.sh update_packages
    :end-before: END manage.sh update_packages
 
@@ -71,7 +71,7 @@ Create a copy of the :origin:`searx/settings.yml` configuration file in system's
 */etc* folder.  Configure like shown below -- replace ``searx@\$(uname -n)`` with
 a name of your choice -- *and/or* edit ``/etc/searx/settings.yml`` if necessary.
 
-.. include:: ../../build/docs/includes/searx.rst
+.. kernel-include:: $DOCS_BUILD/includes/searx.rst
    :start-after: START searx config
    :end-before: END searx config
 
@@ -82,7 +82,7 @@ To check your searx setup, optional enable debugging and start the *webapp*.
 Searx looks at the exported environment ``$SEARX_SETTINGS_PATH`` for a
 configuration file.
 
-.. include:: ../../build/docs/includes/searx.rst
+.. kernel-include:: $DOCS_BUILD/includes/searx.rst
    :start-after: START check searx installation
    :end-before: END check searx installation
 

docs/admin/installation-uwsgi.rst

@@ -104,21 +104,21 @@ restart the uwsgi application.
 
    .. group-tab:: Ubuntu / debian
 
-      .. literalinclude:: ../../build/docs/includes/searx.rst
+      .. kernel-include:: $DOCS_BUILD/includes/searx.rst
          :start-after: START searx uwsgi-description ubuntu-20.04
          :end-before: END searx uwsgi-description ubuntu-20.04
 
 
    .. group-tab:: Arch Linux
 
-      .. literalinclude:: ../../build/docs/includes/searx.rst
+      .. kernel-include:: $DOCS_BUILD/includes/searx.rst
          :start-after: START searx uwsgi-description arch
          :end-before: END searx uwsgi-description arch
 
 
    .. group-tab::  Fedora / RHEL
 
-      .. literalinclude:: ../../build/docs/includes/searx.rst
+      .. kernel-include:: $DOCS_BUILD/includes/searx.rst
          :start-after: START searx uwsgi-description fedora
          :end-before: END searx uwsgi-description fedora
 
@@ -127,22 +127,22 @@ restart the uwsgi application.
 
    .. group-tab:: Ubuntu / debian
 
-      .. literalinclude:: ../../build/docs/includes/searx.rst
-         :language: ini
+      .. kernel-include:: $DOCS_BUILD/includes/searx.rst
+         :code: ini
          :start-after: START searx uwsgi-appini ubuntu-20.04
          :end-before: END searx uwsgi-appini ubuntu-20.04
 
    .. group-tab:: Arch Linux
 
-      .. literalinclude:: ../../build/docs/includes/searx.rst
-         :language: ini
+      .. kernel-include:: $DOCS_BUILD/includes/searx.rst
+         :code: ini
          :start-after: START searx uwsgi-appini arch
          :end-before: END searx uwsgi-appini arch
 
    .. group-tab::  Fedora / RHEL
 
-      .. literalinclude:: ../../build/docs/includes/searx.rst
-         :language: ini
+      .. kernel-include:: $DOCS_BUILD/includes/searx.rst
+         :code: ini
          :start-after: START searx uwsgi-appini fedora
          :end-before: END searx uwsgi-appini fedora
 

docs/utils/filtron.sh.rst

@@ -41,7 +41,7 @@ into this user account:
 Create user
 ===========
 
-.. include:: ../../build/docs/includes/filtron.rst
+.. kernel-include:: $DOCS_BUILD/includes/filtron.rst
    :start-after: START create user
    :end-before: END create user
 
@@ -49,7 +49,7 @@ Create user
 Install go
 ==========
 
-.. include:: ../../build/docs/includes/filtron.rst
+.. kernel-include:: $DOCS_BUILD/includes/filtron.rst
    :start-after: START install go
    :end-before: END install go
 
@@ -61,11 +61,11 @@ Install :origin:`rules.json <utils/templates/etc/filtron/rules.json>` at
 ``/etc/filtron/rules.json`` (see :ref:`Sample configuration of filtron`) and
 install filtron software and systemd unit:
 
-.. include:: ../../build/docs/includes/filtron.rst
+.. kernel-include:: $DOCS_BUILD/includes/filtron.rst
    :start-after: START install filtron
    :end-before: END install filtron
 
-.. include:: ../../build/docs/includes/filtron.rst
+.. kernel-include:: $DOCS_BUILD/includes/filtron.rst
    :start-after: START install systemd unit
    :end-before: END install systemd unit
 

docs/utils/morty.sh.rst

@@ -42,7 +42,7 @@ into this user account:
 Create user
 ===========
 
-.. include:: ../../build/docs/includes/morty.rst
+.. kernel-include:: $DOCS_BUILD/includes/morty.rst
    :start-after: START create user
    :end-before: END create user
 
@@ -50,7 +50,7 @@ Create user
 Install go
 ==========
 
-.. include:: ../../build/docs/includes/morty.rst
+.. kernel-include:: $DOCS_BUILD/includes/morty.rst
    :start-after: START install go
    :end-before: END install go
 
@@ -60,11 +60,11 @@ Install morty
 
 Install morty software and systemd unit:
 
-.. include:: ../../build/docs/includes/morty.rst
+.. kernel-include:: $DOCS_BUILD/includes/morty.rst
    :start-after: START install morty
    :end-before: END install morty
 
-.. include:: ../../build/docs/includes/morty.rst
+.. kernel-include:: $DOCS_BUILD/includes/morty.rst
    :start-after: START install systemd unit
    :end-before: END install systemd unit