Fix README link to homepage
It's actually broken since for whatever reason it's redirecting to
HTTPS://mathquill.com, and GitHub Pages only supports HTTP not HTTPS for
custom domains.
diff --git a/docs/index.md b/docs/index.md
index 320cb38..dda9c9b 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -1,4 +1,4 @@
-# [MathQuill](http://mathquill.github.com)
+# [MathQuill](http://mathquill.com)
by [Han](http://github.com/laughinghan), [Jeanine](http://github.com/jneen), and [Mary](http://github.com/stufflebear) (<maintainers@mathquill.com>)
