Updated PR template to match updated branch model

Author: VesaJuvonen

.github/PULL_REQUEST_TEMPLATE.md

@@ -12,4 +12,4 @@ Please describe the changes in this PR. Sample description or details around bug
 #### Guidance
 *You can delete this section when you are submitting the pull request.* 
 * *Please update this PR information accordingly. We'll use this as part of our release notes in monthly communications.*
-* *Please target your PR to 'staging' branch.*
+* *Please target your PR to 'master' branch. Released documents are in live branch.*