Update pull_request_template.md (#110)

add docs section

Author: typotter

.github/pull_request_template.md

@@ -1,12 +1,16 @@
 [//]: #  (Link to the issue corresponding to this chunk of work)
-Fixes: #__issue__
+:tickets: Fixes __issue__
+:scroll: Design Doc: __link if applicable__
 
 ## Motivation and Context
 [//]: #  (Why is this change required? What problem does it solve?)
 
 ## Description
 [//]: # (Describe your changes in detail)
 
+## How has this been documented?
+[//]: # (Please describe how you documented the developer impact of your changes; link to PRs or issues or explain why no documentation changes are required)
+
 ## How has this been tested?
 [//]: # (Please describe in detail how you tested your changes)