Fixed import source of tags compare function in documentation

Author: squidfunk

Diff for: docs/setup/setting-up-tags.md

@@ -141,7 +141,7 @@ The following configuration options are available:
     ``` yaml
     plugins:
       - tags:
-          tags_compare: !!python/name:material.plugins.tags.plugin.casefold
+          tags_compare: !!python/name:material.plugins.tags.casefold
     ```
 
     You can also define your own comparison function which must return a tag