Proposed Readme Amendments

In attempt to help clarify the project readme, I am submitting a proposed amended version of the readme file. The main purposes are:

- Make "maintenance mode" and submission of PRs (pull requests) less ambiguous
- Include License directly in the Readme
- Include "Who it's For" and "Goal" sections
- Update "How to run" and "How to build" sections

I have forked the project, and will make a commit to my fork, and can submit a PR from there if that is appropriate.

I will include a link to a visual diff showing the proposed changes here:
https://github.com/faginr/Proposed-Readme-Changes/blob/main/Visual%20Diff.pdf

Start by reviewing the project's README and the linked visual diff for the proposed amendments. Update the maintenance mode, pull request, license, Who it's For, Goal, How to run, and How to build sections; done means the README contains the agreed revisions.

Written by the indexing model from the issue text.