TASK: Remove unused intersphinx

* As long as we don't make use of intersphinx disable it to speed up
  rendering of documentation.

Documentation/source/conf.py

@@ -29,7 +29,7 @@ import os
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
 extensions = [
-    'sphinx.ext.intersphinx',
+    # 'sphinx.ext.intersphinx',
     'sphinx.ext.todo',
 ]
 
@@ -310,4 +310,4 @@ texinfo_documents = [
 
 
 # Example configuration for intersphinx: refer to the Python standard library.
-intersphinx_mapping = {'https://docs.python.org/': None}
+# intersphinx_mapping = {'https://docs.python.org/': None}