gnucash-on-windows master: Add info about building other branches and using cmake + ninja.

[John Ralls]

Updated	 via  https://github.com/Gnucash/gnucash-on-windows/commit/8d412fa8 (commit)
	from  https://github.com/Gnucash/gnucash-on-windows/commit/cff2538d (commit)



commit 8d412fa8112b2a39f6a91cfdb8895a91f55db1e1
Author: John Ralls <jralls at ceridwen.us>
Date:   Sat Apr 15 12:30:12 2017 -0700

    Add info about building other branches and using cmake + ninja.



Summary of changes:
 README | 7 +++++++
 1 file changed, 7 insertions(+)