Added some slight descriptions to the links in legacy-dev page.

Author: Stewori

legacy-dev.md

@@ -4,8 +4,10 @@ title: Legacy
 ## Development before move to Github
 
 ### [Bug tracker](https://bugs.jython.org/)
+Good old “bjo” bugs.jython.org.
 
 ### [Mercurial](https://hg.python.org/jython/)
+Until June 2020, development took place here.
 
 ### [Github mirror](https://github.com/jython/frozen-mirror/)
 This mirror is now frozen.