hg: jdk9/sandbox: 2 new changesets

[magnus.ihse.bursie at oracle.com]

Changeset: 3b540385689a
Author:    ihse
Date:      2017-03-10 14:50 +0100
URL:       http://hg.openjdk.java.net/jdk9/sandbox/rev/3b540385689a

Clean up markdown in building.md.

! common/doc/building.html
! common/doc/building.md

Changeset: 4f4972476644
Author:    ihse
Date:      2017-03-10 14:54 +0100
URL:       http://hg.openjdk.java.net/jdk9/sandbox/rev/4f4972476644

Turn top-level README into proper markdown.

! README