Redesign website (#2628)

* Bump up Bootstrap to v5.3.1, Bootstrap Icon to v1.10.5.
* Use autoComplete.js to drop dependency on jQuery and typeahead.js.
* Support dark mode.
* New svg logo and icon with responsive color mode support.
* Normalize section ids to lower kebab-case for easiness of linking.
* Use relative paths for links for local development (--root /output).
* Various markup cleanups and accessibility improvements.

docs/content/manual/v1.6/manual.yml

@@ -4,7 +4,7 @@ headline: jq 1.6 Manual
 history: |
 
   *The manual for the development version of jq can be found
-  [here](/jq/manual).*
+  [here](../).*
 
 body: |