Improve layout of documentation page and add search feature (#8247)

* Improve layout of documentation page and add search feature

Closes https://github.com/FreshRSS/FreshRSS/issues/7915, https://github.com/FreshRSS/FreshRSS/issues/5325

Also: anchor headings and fix building site locally

* Further improvements

* Set color of hyperlinks
* Consistent styling of close aside button across devices
* Mobile layout 600px -> 1200px
* Add suffix to docs `<title>`
    * Note: titles of pages probably need to be improved, since currently they are just derived from the names of the first heading on every page
* Add favicon

* Improve font

* Try to fix favicon not loading correctly on GH pages

* Use local font

* Attempt to fix GH pages

* Final improvements

* Copy to clipboard button
* Support for nojs search
* Dark mode
* Load search.json (200KB json) only on search input focus
* Keep scroll state of sidebar across navigations

* Clickable images and CSP

CSP so we avoid hotlinking resources and clickable images are useful for zooming on mobile for example

* Fix typos

* Disable Dark Reader extension if dark mode CSS is loaded

* Support internationalisation (via language dropdown)

* Add Gemfile.lock

* Make CI build work with the custom plugin

* Make menus closable with Esc

* Fix typos CI

* Suggestions

* Use `ruby/setup-ruby` action in workflow for installing and caching gems.

* Run build only when there are changes to `docs/`

See: https://docs.github.com/en/actions/reference/workflows-and-actions/events-that-trigger-workflows?versionId=free-pro-team%40latest&productId=actions#running-your-workflow-only-when-a-push-to-specific-branches-occurs

* Change font to `Open Sans`

* Increase line height

* Fix Liquid syntax error

1 files changed, 77 insertions, 0 deletions

diff --git a/docs/_includes/docs_nav.html b/docs/_includes/docs_nav.html
new file mode 100644
index 000000000..3b3083c1e
--- /dev/null
+++ b/docs/_includes/docs_nav.html
@@ -0,0 +1,77 @@
+{% if page.lang == 'en' %}
+	<ul>
+		<li><a href="{{ '/en/' | relative_url }}">Home</a></li>
+		<li>
+			<a href="{{ '/en/users/02_First_steps.html' | relative_url }}">User documentation</a>
+			<ul>
+				{% for page in site.pages %}
+					{% if page.url contains '/en/users/' and page.title != nil and page.url != "/en/users/02_First_steps.html" %}
+						<li><a href="{{ page.url | relative_url }}">{{ page.title | escape }}</a></li>
+					{% endif %}
+				{% endfor %}
+			</ul>
+		</li>
+		<li>
+			<a href="{{ '/en/admins/01_Index.html' | relative_url }}">Administrator documentation</a>
+			<ul>
+				{% for page in site.pages %}
+					{% if page.url contains '/en/admins/' and page.url != "/en/admins/01_Index.html" and page.title != nil %}
+						<li><a href="{{ page.url | relative_url }}">{{ page.title | escape }}</a></li>
+					{% endif %}
+				{% endfor %}
+			</ul>
+		</li>
+		<li>
+			<a href="{{ '/en/developers/01_Index.html' | relative_url }}">Developer documentation</a>
+			<ul>
+				{% for page in site.pages %}
+					{% if page.url contains '/en/developers/' and page.url != "/en/developers/01_Index.html" and page.title != nil %}
+						<li><a href="{{ page.url | relative_url }}">{{ page.title | escape }}</a></li>
+					{% endif %}
+				{% endfor %}
+			</ul>
+		</li>
+		<li>
+			<a href="{{ '/en/contributing.html' | relative_url}}">Contributor guidelines</a>
+		</li>
+	</ul>
+{% elsif page.lang == 'fr' %}
+	<ul>
+		<li><a href="{{ '/fr/' | relative_url }}">Accueil</a></li>
+		<li>
+			<a href="{{ '/fr/users/02_First_steps.html' | relative_url }}">Documentation utilisateur</a>
+			<ul>
+				{% for page in site.pages %}
+					{% if page.url contains '/fr/users/' and page.title != nil and page.url != "/fr/users/02_First_steps.html" %}
+						<li><a href="{{ page.url | relative_url }}">{{ page.title | escape }}</a></li>
+					{% endif %}
+				{% endfor %}
+			</ul>
+		</li>
+		<!-- TODO: French doesn't have admin docs -->
+		<!-- <li> -->
+			<!-- <a href="{{ '/fr/admins/01_Index.html' | relative_url }}">Administrator documentation</a> -->
+			<!-- <ul> -->
+				<!-- {% for page in site.pages %} -->
+					<!-- {% if page.url contains '/fr/admins/' and page.url != "/fr/admins/01_Index.html" and page.title != nil %} -->
+						<!-- <li><a href="{{ page.url | relative_url }}">{{ page.title | escape }}</a></li> -->
+					<!-- {% endif %} -->
+				<!-- {% endfor %} -->
+			<!-- </ul> -->
+		<!-- </li> -->
+		<li>
+			<a href="{{ '/fr/developers/01_First_steps.html' | relative_url }}">Documentation développeur</a>
+			<ul>
+				{% for page in site.pages %}
+					{% if page.url contains '/fr/developers/' and page.url != "/fr/developers/01_First_steps.html" and page.title != nil %}
+						<li><a href="{{ page.url | relative_url }}">{{ page.title | escape }}</a></li>
+					{% endif %}
+				{% endfor %}
+			</ul>
+		</li>
+		<li>
+			<a href="{{ '/fr/contributing.html' | relative_url}}">Directives pour les contributeurs</a>
+		</li>
+	</ul>
+{% endif %}
+