[fix] typo in doc-str: offical -> official

searx/engines/soundcloud.py

@@ -23,7 +23,7 @@ categories = ["music"]
 paging = True
 
 search_url = "https://api-v2.soundcloud.com/search"
-"""This is not the offical (developer) url, it is the API which is used by the
+"""This is not the official (developer) url, it is the API which is used by the
 HTML frontend of the common WEB site.
 """