DOC: Browser-based editing is now available via GitHub

And the "Edit this page" functionality via the Sphinx extension.

Author: thewtex

README.rst

@@ -43,13 +43,11 @@ Implemented
 - Script to create a new examples from a template.
 - GitHub community development.
 - Selectable light/dark colorscheme.
+- Online editing via GitHub.
 
 Todo
 ^^^^
 
-- Anonymous online editing.
-- Editable online with CodeMirror.
-
 - See `Github Issues`_ for a complete list of actions to be performed, bugs, *etc.*
 
 Build dependencies