Docs: Remove Instant Navigation for now.

There is an issue where only the first anchor navigation works correctly, and subsequent ones always try to open in a new tab.

There were reports that this was fixed, e.g. squidfunk/mkdocs-material#6662. However, it appears to have either regressed or not been fully tested.

mkdocs.yml

@@ -3,9 +3,6 @@ site_url: https://focustense.github.io/StardewUI
 repo_url: https://github.com/focustense/StardewUI
 theme:
   name: material
-  features:
-    - navigation.instant
-    - navigation.instant.progress
   palette:
     - media: "(prefers-color-scheme)"
       toggle: