In support of moving the jfx 11 updates development to GitHub we need a new `README.md` and `CONTRIBUTING.md` files at the top of the openjfx/11-dev/rt repo.

These files will be newly created for the jfx 11 updates release, rather than a backport from the mainline jfx repo, since the contents will be completely different. For update releases, the emphasis is not on accepting new contributions, but on backporting selected changes, and the documents will reflect that.

Here is a draft pull request for review of these two new files:

https://github.com/kevinrushforth/jfx/pull/2

Note that the PR is just for review. This will be pushed to the existing HG repo prior to the switch to GIT.