Update README.md to reflect BRD4(1) changes

[davidlmobley]

@GHeinzelmann - this is what I was talking about. It's just updating a sort of "change log" in the main README.md to reflect what we've changed here. Since these changes are not yet in a release version, they are reflected in the "changes not yet in a release" section of the README.

[GHeinzelmann]

Oh I see, it is the main README file in the main directory! I thought you meant the one from the input files, but it makes sense to add the new changes that are not yet in a release to then main README so we can keep track of them.

[davidlmobley]

Right. Now, momentarily, I'll do anotehr PR which incorporates these into a "version 1.3" release, update the version number in the PDF, then do a formal "release" using the "releases" tab under "code" on GitHub. This makes it so the release gets a DOI and is permanently archived so people can refer to that specific version easily.

[GHeinzelmann]

Hm now I understand. I thought the archived releases were only in the eScholarship site, and on GitHub the master branch would be equivalent to the latest version, without an associated DOI. But that is good to know, next time I will already be familiar with how it works, making everything quicker.