docs: Setup template for release note process

Add some guidelines for release notes that developers can use to create
release note snippets as features and fixes are implemented.  This will
greatly reduce the work needed at release time.

Signed-off-by: David Brown <david.brown@linaro.org>
diff --git a/docs/release.md b/docs/release.md
index 170c9b8..48b555c 100644
--- a/docs/release.md
+++ b/docs/release.md
@@ -24,6 +24,12 @@
 to describe the release. This should be a high-level description of
 the changes, not a list of the git commits.
 
+Provided that changes going into the release have followed the
+contribution guidelines, this should mostly consist of collecting the
+various snippets in the `docs/release-notes.d` directory.  After
+incorporating these snippets into the release notes, the snippet files
+should be removed to ready the directory for the next release cycle.
+
 ## Release candidates
 
 Before each release, tags are made (see below) for at least one