docs: Fix several MkDocs info and warning messages (#3663)

* docs: Fix nav error in mkdocs.yml

This commit fixes the informational message logged by MkDocs due to an
incorrect format in the nav parameter.

> Config value 'nav': Expected nav to be a list, got dict with keys...

* docs: Update pymdownx.emoji extensions

This commit resolves the following informational from MkDocs that was
being logged due to the previous extensions no longer being supported.

  Material emoji logic has been officially moved into mkdocs-material
  version 9.4. Please use Material's 'material.extensions.emoji.twemoji'
  instead of 'materialx.emoji.twemoji' in your 'mkdocs.yml' file.

* docs: Fix warning for invalid 'trademark' config

PR #3132 (commit 8285041) introduced a trademark disclaimer to the
website's footer, storing the trademark URL in MkDocs config under the
key `config.trademark`.

This is not a valid MkDocs configuration parameter and causes the
following warning to be logged when building the site.

  WARNING -  Config value 'trademark': Unrecognised configuration name:
  trademark

The correct place to store custom configuration is under the `extra`
key [1] in MkDoc's configuration.

This commit relocates `trademark` parameter to resolve the
configuration warning.

[1]: https://www.mkdocs.org/user-guide/configuration/#extra

* docs: Ignore certain files from nav config

MkDocs currently logs an informational message stating that files under
the blog/ and gep-696/ (GEP template) paths are not present in the
site's navigation.

  The following pages exist in the docs directory, but are not included
  in the "nav" configuration:

This commit adds MkDocs's `not_in_nav` configuration parameter to
specify that these paths are intentionally excluded from the site's
navigation.

Author: blake

mkdocs.yml

@@ -3,7 +3,8 @@ repo_url: https://github.com/kubernetes-sigs/gateway-api
 repo_name: kubernetes-sigs/gateway-api
 site_dir: site
 docs_dir: site-src
-trademark: https://www.linuxfoundation.org/legal/trademark-usage
+extra:
+  trademark: https://www.linuxfoundation.org/legal/trademark-usage
 extra_css:
   - stylesheets/extra.css
 extra_javascript:
@@ -52,8 +53,8 @@ markdown_extensions:
   - admonition
   - meta
   - pymdownx.emoji:
-      emoji_index: !!python/name:materialx.emoji.twemoji
-      emoji_generator: !!python/name:materialx.emoji.to_svg
+      emoji_index: !!python/name:material.extensions.emoji.twemoji
+      emoji_generator: !!python/name:material.extensions.emoji.to_svg
   - pymdownx.details
   - pymdownx.highlight
   - pymdownx.inlinehilite
@@ -70,17 +71,17 @@ nav:
   - Overview:
     - Introduction: index.md
     - Concepts:
-        API Overview: concepts/api-overview.md
-        Conformance: concepts/conformance.md
-        Roles and Personas: concepts/roles-and-personas.md
-        Security Model: concepts/security-model.md
-        Tools: concepts/tooling.md
-        Use Cases: concepts/use-cases.md
-        Versioning: concepts/versioning.md
+      - API Overview: concepts/api-overview.md
+      - Conformance: concepts/conformance.md
+      - Roles and Personas: concepts/roles-and-personas.md
+      - Security Model: concepts/security-model.md
+      - Tools: concepts/tooling.md
+      - Use Cases: concepts/use-cases.md
+      - Versioning: concepts/versioning.md
     - Service Mesh:
-        Overview: mesh/index.md
-        GAMMA Initiative: mesh/gamma.md
-        Service Facets: mesh/service-facets.md
+      - Overview: mesh/index.md
+      - GAMMA Initiative: mesh/gamma.md
+      - Service Facets: mesh/service-facets.md
     - Implementations:
         - List: implementations.md
         - Comparisons:
@@ -180,3 +181,6 @@ nav:
     - Enhancement Requests: contributing/enhancement-requests.md
     - Release Cycle: contributing/release-cycle.md
     - Contributor Ladder: contributing/contributor-ladder.md
+not_in_nav: |
+  /blog/*
+  /geps/gep-696/*

site-src/overrides/partials/copyright.html

@@ -22,10 +22,10 @@
 
 <!-- Copyright and theme information -->
 <div class="md-copyright">
-  {% if config.trademark %}
+  {% if config.extra.trademark %}
   <p>
     The Linux Foundation has registered trademarks and uses trademarks. For a list of trademarks of The Linux Foundation,
-    please see our <a href="{{ config.trademark }}">Trademark Usage page</a>.
+    please see our <a href="{{ config.extra.trademark }}">Trademark Usage page</a>.
   </p>
   {% endif %}
   {% if not config.extra.generator == false %}