Readme stub for github

Github uses readmes for its front page so providing a little pointer to our site. https://trac.torproject.org/projects/tor/ticket/26224

Readme stub for github
df750724 · Damian Johnson · 8ec17d80 · df750724
Commit df750724 authored Aug 5, 2018 by Damian Johnson
--- a/README.md
+++ b/README.md
+## Stem (Python Tor Library)
+
+
+Stem is a Python controller library for **[Tor](https://www.torproject.org/)**. With it you can use Tor's [control protocol](https://gitweb.torproject.org/torspec.git/tree/control-spec.txt) to script against the Tor process, or build things such as [Nyx](https://nyx.torproject.org/).
+
+Documentation and tutorials available at **[stem.torproject.org](https://stem.torproject.org/)**.