Enable auto-cross-referencing

[rtopfer]

Once a Documentor instance has been initialized (the documentation content drafted and the output file structure assigned), the drafted documentation could be scanned for keywords (e.g. names of the assigned functions,scripts,classes, etc.) and cross-referencing relative links could be inserted (e.g. first instance of a keyword in a given entry, and/or into the standard % See also footer)

Requires deciding which among the approaches listed here would be easiest to use.

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Separate but related feature request:
Auto-addition of hyperlinks to the corresponding GitHub code would be a nice option

E.g. the URL to the .m file could be included beneath the doc title + synopsis.

If the file structure is kept the same (i.e. doc directory tree mirrors that of the code) or simply if a key-map was output by the documentation process (i.e. this .md entry correspond to that .m file) then it should be reasonably straightforward? Is this something readthedocs or git/GitHub already support?