fix: Change Wikiversity and Wikivoyage shortcuts to wv and wy.

Suggested by @Venca24 <https://github.com/asciimoo/searx/pull/1914#issuecomment-610194209>.

searx/settings.yml

@@ -733,7 +733,7 @@ engines:
 
   - name : wikiversity
     engine : mediawiki
-    shortcut : wvs
+    shortcut : wv
     categories : general
     base_url : "https://{language}.wikiversity.org/"
     number_of_results : 5
@@ -742,7 +742,7 @@ engines:
 
   - name : wikivoyage
     engine : mediawiki
-    shortcut : wvy
+    shortcut : wy
     categories : general
     base_url : "https://{language}.wikivoyage.org/"
     number_of_results : 5