Improve keyword notation of Texinfo function definitions.

Improve keyword notation of Texinfo function definitions.

* doc/ref/api-debug.texi:
* doc/ref/api-evaluation.texi:
* doc/ref/api-modules.texi:
* doc/ref/compiler.texi:
* doc/ref/web.texi: Make Texinfo function headers more consistent.
  Change lesser used keyword notation to the predominant form.

* doc/ref/api-procedures.texi: Fix an argument name in a header that should
  use repeated argument notation.

* doc/ref/srfi-modules.texi: Update references in Texinfo function
  definition body to match previously updated variable notation in
  definition header.