Update social card for Jellyfin, add search highlighting

manuscript/recipes/jellyfin.md

@@ -1,3 +1,6 @@
+---
+description: Jellyfin is best described as "like Emby but really FOSS". It started as an Emby fork, but has evolved significantly since then, with its own advantages over Emby.
+---
 # Jellyfin
 
 [Jellyfin](https://jellyfin.org/) is best described as "_like [Emby](/recipes/emby) but really [FOSS](https://en.wikipedia.org/wiki/Free_and_open-source_software)_".

mkdocs.yml

@@ -188,11 +188,11 @@ theme:
   favicon: 'images/site-logo.svg'
   features:
       - navigation.tabs
-#      - navigation.instant 
+      - navigation.instant 
       - navigation.tabs.sticky  
       - navigation.sections
       - search.suggest
-#      - search.highlight
+      - search.highlight
       - search.share
   icon:
     repo: 'fontawesome/brands/github'