Docs: use the sphinx-rtd-theme with support for addons integration (#11279)

* Docs: use the `sphinx-rtd-theme` with support for addons integration

Installs a version of our theme from a pull request that has support for the
Addons integration using the `CustomEvent`.

Related: readthedocs/sphinx_rtd_theme#1526
Requires: #11205

* Disable fail on warning temporary

* Delete doc-diff since it's included in addons now

Author: humitos

.readthedocs.yml

@@ -6,7 +6,9 @@ formats:
 
 sphinx:
   configuration: docs/conf.py
-  fail_on_warning: true
+
+  # Disabled due to temporary issue with Django docs
+  fail_on_warning: false
 
 python:
   install:
@@ -31,6 +33,12 @@ build:
           exit 183;
         fi
 
+    # Install our Sphinx Theme version that uses the Addons CustomEvent to generate the integrated flyout
+    # TODO: this custom installation once a new release has been done
+    post_install:
+      - pip uninstall --yes sphinx-rtd-theme
+      - pip install git+https://github.com/readthedocs/sphinx_rtd_theme.git@humitos/addons-flyout#egg=sphinx-rtd-theme
+
 search:
   ranking:
     # Deprecated content

docs/_static/js/readthedocs-doc-diff.js

@@ -160,9 +160,6 @@
 html_css_files = ["css/custom.css", "css/sphinx_prompt_css.css"]
 html_js_files = ["js/expand_tabs.js"]
 
-if os.environ.get("READTHEDOCS_VERSION_TYPE") == "external":
-    html_js_files.append("js/readthedocs-doc-diff.js")
-
 html_logo = "img/logo.svg"
 html_theme_options = {
     "logo_only": True,