Link to the new translation mailing list from README.md

Weaken and clarify the wording a bit, it currently implies that we get
more pull requests than we can ever handle which discourages
contribution.

How could I forgot this file...

Added some help text, and bumped version numbers.

Added a Readable Index for /Contrib

Fixing /Contrib Index URLs

Revert Version Numbers.

* updated references to files which have since been moved
* added reference to licensing
* added brief summary in case a non-technical user happens upon repo first
* miscellaneous Markdown-isms to make the doc more attractive
* remove unused symlink README -> README.md

I double-checked the makefiles and whatnot to ensure that the README symlink is
not being referenced. It is not. Rather, `doc/README` and
`doc/README_windows.txt` are copied for distribution.