For the HTML version, click here.
See the ChangeLog file for the version number and changes by release.
fontname.texi is the master source, a Texinfo document describing the overall scheme. fontname.info is the Info version.
The *.map files contain tables of abbreviations and font lists. They are mostly described in fontname.texi.
The *.enc files are encoding files for use with Afm2tfm, which comes with dvips.