Disable Stars config option (#14653)

* Add config option to disable stars

* Replace "stars" with watched in user profile

* Add documentation

custom/conf/app.example.ini

@@ -70,6 +70,8 @@ PREFIX_ARCHIVE_FILES = true
 DISABLE_MIRRORS = false
 ; Disable migrating feature.
 DISABLE_MIGRATIONS = false
+; Disable stars feature.
+DISABLE_STARS = false
 ; The default branch name of new repositories
 DEFAULT_BRANCH = master
 ; Allow adoption of unadopted repositories