docs: Add sphinx-sitemap generation to Python doc (#5331)

Added sitemap for Sphinx docs using the sphinx-sitemap extension to address part of issue #5321. Includes the corresponding change in CI.

The results are a basic sitemap with each URL. Leaving out pages according to the example in documentation. Not including lastmod which is in our current site maps because this is not currently supported by Sphinx (but in it is  works).

Author: cwhite911

.github/workflows/documentation.yml

@@ -153,7 +153,7 @@ jobs:
 
       - name: Build Sphinx documentation
         run: |
-          pip install sphinx
+          pip install sphinx sphinx-sitemap
           cd grass
           make sphinxdoclib
           ARCH="$(grass --config arch)"

python/grass/docs/conf.py

@@ -112,6 +112,7 @@
     "sphinx.ext.mathjax",
     "sphinx.ext.ifconfig",
     "sphinx.ext.viewcode",
+    "sphinx_sitemap",
 ]
 
 # Add any paths that contain templates here, relative to this directory.
@@ -135,7 +136,7 @@
 # built documents.
 #
 # The short X.Y version.
-# version = '0.1'
+version = grass_version
 # The full version, including alpha/beta/rc tags.
 # release = '0.1'
 
@@ -431,3 +432,14 @@
 
 # Where class documentation comes from (class or __init__ docstring).
 autoclass_content = "both"
+
+# sphinx-sitemap extension config
+# https://sphinx-sitemap.readthedocs.io/en/latest/advanced-configuration.html
+sitemap_filename = "sitemap.xml"
+html_baseurl = "https://grass.osgeo.org/"
+sitemap_url_scheme = "grass{version}manuals/libpython/{link}"
+
+sitemap_excludes = [
+    "search.html",
+    "genindex.html",
+]