Formatted READMEs

I’ve set up the README files for my WordPress plugins so they are formatted nicely now instead of the plain text representation that was there before.

For the curious, before and after.

In addition, the README links for each plugin on the plugins page will now show the README for the latest official release, even if I forget to update the link. :)

Hopefully better presentation will prompt folks to actually read the README when they have a problem; but I may be dreaming here. ;)