docs: add prototype sphinx extension for online help

goes through the sections in the documents and creates the
OnlineHelpInfo.js file from the explicitly defined section labels which
are used in the js files with 'onlineHelp' variable.

docs/conf.py

@@ -18,9 +18,12 @@
 # documentation root, use os.path.abspath to make it absolute, like shown here.
 #
 import os
-# import sys
+import sys
 # sys.path.insert(0, os.path.abspath('.'))
 
+# custom extensions
+sys.path.append(os.path.abspath("./_ext"))
+
 # -- Implement custom formatter for code-blocks ---------------------------
 #
 # * use smaller font
@@ -46,7 +49,7 @@ PygmentsBridge.latex_formatter = CustomLatexFormatter
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
 
-extensions = ["sphinx.ext.graphviz", "sphinx.ext.todo"]
+extensions = ["sphinx.ext.graphviz", "sphinx.ext.todo", "proxmox-scanrefs"]
 
 todo_link_only = True