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
diff --git a/Doc/Makefile b/Doc/Makefile
index eb62df5..94697f9 100644
--- a/Doc/Makefile
+++ b/Doc/Makefile
@@ -153,7 +153,7 @@
 	cp -pPR build/epub/Python.epub dist/python-$(DISTVERSION)-docs.epub
 
 check:
-	$(PYTHON) tools/rstlint.py -i tools -i venv
+	$(PYTHON) tools/rstlint.py -i tools -i venv -i README.rst
 
 serve:
 	../Tools/scripts/serve.py build/html