Make the link to spec index a link, and update the URL as well.

Fixes w3c#1315.

Author: dbaron

README.markdown

@@ -7,12 +7,11 @@ This repository is a two-way mirror of a Mercurial repository:
         hg clone https://hg.csswg.org/drafts
 
 For help using or setting up Mercurial 
-see instructions [here](http://wiki.csswg.org/tools/hg).  
+see [instructions](http://wiki.csswg.org/tools/hg).
 Specification issues are discussed as issues in this repo. 
 General CSSWG discussion can be found on the public 
 [www-style mailing list](http://lists.w3.org/Archives/Public/www-style/).
 
-For an index of all specifications, see:
-
-        http://dev.w3.org/csswg/
+To read the specifications in this repository, see them at the
+[index of all specifications](https://drafts.csswg.org/).