Rename Doc/README.txt to Doc/README.rst and add formatting (#104)

* Reformat Doc/README.txt to Doc/README.rst

* Update mention of Doc/README.rst

* Update mention of README.txt to README.rst

* Make line fold

* rstlint ignore Doc/README.rst

* conf.py ignore Doc/README.rst

* Update issue tracker url in Docs/README.rst
5 files changed