fix: place the las_update value in the meta of each page

docs/conf.py

@@ -92,6 +92,7 @@
 html_logo = "_static/logo.svg"
 html_favicon = "_static/logo.svg"
 html_sourcelink_suffix = ""
+html_last_updated_fmt = ""  # to reveal the build date in the pages meta
 
 # Define the json_url for our version switcher.
 json_url = "https://pydata-sphinx-theme.readthedocs.io/en/latest/_static/switcher.json"

docs/user_guide/layout.rst

@@ -567,3 +567,18 @@ could do so with the following steps:
       "navbar_start": ["navbar-logo", "version"],
       # ...
       }
+
+Build date
+==========
+
+By default the build date cannot be seen in our template even when the `html_last_updated_fmt <https://www.sphinx-doc.org/en/master/usage/configuration.html#confval-html_last_updated_fmt>`__ is set. Instead the theme adds a ``meta`` tag in the HTML head that specifies the build date, which can be inspected by viewing the page source or extracted with an HTML parser. The tag will look like:
+
+.. code-block:: html
+
+    <meta name="docbuild:last-update" content="Aug 15, 2023">
+
+The tag's ``content`` attribute will follow the format specified in the ``html_last_updated_fmt`` configuration variable.
+
+.. note::
+
+    If a special component to display such an information in your page is your need please use the built-in :code:`last-updated`.

src/pydata_sphinx_theme/theme/pydata_sphinx_theme/layout.html

@@ -39,6 +39,9 @@
 {%- block extrahead %}
   <meta name="viewport" content="width=device-width, initial-scale=1"/>
   <meta name="docsearch:language" content="{{ language }}"/>
+  {%- if last_updated %}
+    <meta name="docbuild:last-update" content="{{ last_updated | e }}"/>
+  {%- endif %}
 {%- endblock extrahead %}
 {% block body_tag %}
   {# set up with scrollspy to update the toc as we scroll #}