Upgrade DITA-OT Gradle Plugin to v0.6.0
Upgrade DITA-OT Gradle Plugin to v0.6.0

https://github.com/eerohele/dita-ot-gradle/issues/19

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

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