doc: add RTD version-switch div on furo theme

Signed-off-by: Xavier Delaruelle <xavier.delaruelle@cea.fr>

doc/source/_templates/sidebar/brand.html

@@ -0,0 +1,22 @@
+<a class="sidebar-brand{% if logo %} centered{% endif %}" href="{{ pathto(master_doc) }}">
+  {%- block brand_content %}
+  {#- Remember to update the prefetch logic in `block logo_prefetch_links` in base.html #}
+  {%- if logo_url %}
+  <div class="sidebar-logo-container">
+    <img class="sidebar-logo" src="{{ logo_url }}" alt="Logo"/>
+  </div>
+  {%- endif %}
+  {%- if theme_light_logo and theme_dark_logo %}
+  <div class="sidebar-logo-container">
+    <img class="sidebar-logo only-light" src="{{ pathto('_static/' + theme_light_logo, 1) }}" alt="Light Logo"/>
+    <img class="sidebar-logo only-dark" src="{{ pathto('_static/' + theme_dark_logo, 1) }}" alt="Dark Logo"/>
+  </div>
+  {%- endif %}
+  {% if not theme_sidebar_hide_name %}
+  <span class="sidebar-brand-text">{{ docstitle if docstitle else project }}</span>
+  {%- endif %}
+  {% endblock brand_content %}
+</a>
+{%- if READTHEDOCS %}
+<div class="version-switch"></div>
+{%- endif %}

doc/source/conf.py

@@ -140,6 +140,9 @@ if os_rtd:
         'light_logo': 'modules_red.svg',
         'dark_logo': 'modules_white.svg',
     }
+    html_context = {
+        'READTHEDOCS': True,
+    }
 
 # The name of an image file (relative to this directory) to place at the top
 # of the sidebar.