Add a link to the user survey

Author: pieter

Documentation/ReleaseNotes/v0.7.txt

@@ -1,6 +1,10 @@
 v0.7
 ===
 
+As a GitX user, we would like you to help us focus our development by telling
+us your wishes. You can help us by filling in this
+ [survey](http://www.survs.com/survey?id=DCJKLP2B&channel=UY6RRC3MXZ "GitX User survey")!
+
 This feature-release has the following new features and enhancements:
 
 * Line-wise staging by selecting lines from hunks (JD Smith)