Add new autorefs plugin option to resolve_closest

When multiple URLs were found for a autoref, the plugin emits a warning,
which in our setup breaks the build as we use strict mode. This new
option allows to resolve the reference to the "closest URL".

See the documentation for more information:
https://github.com/mkdocstrings/autorefs#non-unique-headings

Signed-off-by: Leandro Lucarella <luca-frequenz@llucax.com>

mkdocs.yml

@@ -87,6 +87,8 @@ markdown_extensions:
       permalink: "¤"
 
 plugins:
+  - autorefs:
+      resolve_closest: true
   - gen-files:
       scripts:
         - docs/_scripts/mkdocstrings_autoapi.py