Fix logback version key
Fix logback version key

Amends 9610a0d.

Signed-off-by: Roger Sheen <a61a1add71dadc74037ae5e44ee30713db9a7451@infotexture.net>

shaneataylor/docs,shaneataylor/docs,infotexture/docs,infotexture/docs,dita-ot/docs