sphinx: add support to generate click CLI doc

requirements.txt

@@ -9,3 +9,4 @@ sphinxcontrib-programoutput
 sphinx-tabs
 recommonmark
 sphinx_rtd_theme
+sphinx-click

swh/docs/sphinx/conf.py

@@ -26,6 +26,7 @@ extensions = [
     "sphinx_tabs.tabs",
     "sphinx_rtd_theme",
     "sphinx.ext.graphviz",
+    "sphinx_click.ext",
 ]
 
 # Add any paths that contain templates here, relative to this directory.