I had a docstring containing "C-c". Checkdoc gave me this suggestion:
"Keycode C-c embedded in doc string.  Use \\<keymap> & \\[function] instead"

Ok, but how? The relevant page of Elisp reference is (info "(elisp) Keys 
in Documentation"). But there they're called ‘\<MAPVAR>’ and 
‘\[COMMAND]’. So someone searching by the checkdoc names would never 
find them there. The docstring for substitute-command-keys is also 
consistent with the Elisp reference.

A trivial patch is included, since Elisp reference names seem more 
reasonable.

I'm not sure whether MAPVAR and COMMAND should be capitalized in the 
docstring, so someone else should decide on that.