add diffplug#49 to changes.md

Author: hacki11

CHANGES.md

@@ -2,6 +2,8 @@
 
 ### Version 3.10.0 - TBD ([javadoc](http://diffplug.github.io/goomph/javadoc/snapshot/), [snapshot](https://oss.sonatype.org/content/repositories/snapshots/com/diffplug/gradle/goomph/))
 
+- Added a feature to provide a custom goomph-pde-bootstrap installation. [(#49)](https://github.com/diffplug/goomph/pull/52)
+
 ### Version 3.9.1 - February 2nd 2018 ([javadoc](http://diffplug.github.io/goomph/javadoc/3.9.1/), [jcenter](https://bintray.com/diffplug/opensource/goomph/3.9.1/view))
 
 - Added `--launcher.suppressErrors` to all `EclipseApp` invocations so that build errors won't open a blocking dialog on build servers. [(#49)](https://github.com/diffplug/goomph/pull/49)