Target user doc 4.6 instead of master (#2618)

Author: adriendupuis

mkdocs.yml

@@ -939,7 +939,7 @@ extra:
   latest_tag_4_6: '4.6.17'
 
   symfony_doc: 'https://symfony.com/doc/5.x'
-  user_doc: 'https://doc.ibexa.co/projects/userguide/en/master'
+  user_doc: 'https://doc.ibexa.co/projects/userguide/en/4.6'
   connect_doc: 'https://doc.ibexa.co/projects/connect/en/latest'
 
 extra_css: