Rename README to README.md

[davelab6]

This enables inline github rendering of the markdown syntax used

You can see how it looks here:

https://github.com/davelab6/harfpy/tree/patch-1

[ldo]

It is traditional for README to be called README, not README.md. Think of the latter as a GitHubism. I don’t want to tie my development too closely into GitHub!

[davelab6]

But your file is written in markdown; its general best practice to use a file extension that expresses the contents of the file

[ldo]

Markdown is just text. It is meant to be human-readable as is.