Reference to missing API.txt

A piddly detail.

In gmap/README.txt:
Line 65: A GMap macro will look something like this (see API.txt for syntax details)
Line 72: Again, see API.txt for syntax details.

However, API.txt is non-existent in gmap-6.x-1.0.tar.gz, but does exist in gmap-5.x-1.0.tar.gz. API.txt in gmap-6.x-1.0.tar.gz has been replaced with gmap/help/API.html, but the documentation does not reflect this.