Merge pull request #4374 from tgross35/pr-template

Add links to common header sources in the PR template

Author: tgross35

.github/PULL_REQUEST_TEMPLATE.md

@@ -12,8 +12,20 @@ Please fill out the below template.
 
 # Sources
 
-<!-- All API changes must have links to headers and/or documentation,
-preferably both -->
+<!-- All API changes must have permalinks to headers. Common sources:
+
+* Linux uapi https://github.com/torvalds/linux/tree/master/include/uapi
+* Glibc https://github.com/bminor/glibc
+* Musl https://github.com/bminor/musl
+* Apple XNU https://github.com/apple-oss-distributions/xnu
+* Android https://cs.android.com/android/platform/superproject/main
+
+After navigating to the relevant file, click the triple dots and select "copy
+permalink" if on GitHub, or l-r (links->commit) for the Android source to get a
+link to the current version of the header.
+
+If sources are closed, link to documentation or paste relevant C definitions.
+-->
 
 # Checklist