Auto-generate keyboard shortcuts in helpdata.txt

[jwrober]

Is your feature request related to a problem? Please describe.
Maintaining the list of keyboard shortcuts available from the client in help is very time consuming.

Describe the solution you'd like
It would be better for the code to do this so as changes are made there, the help is automagically updated. This could in the form of a single page with a generated table, or better yet, as a generated section of pages like we do for wonders, or city improvements.

Describe alternatives you've considered
Right now we manually manage this and some automation would be much better.

Additional context
None