Make ChangeLog more visible in PR template

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>

.github/pull_request_template.md

diff --git a/.github/pull_request_template.md b/.github/pull_request_template.md
index c580443..9bc3b0a 100644
--- a/.github/pull_request_template.md
+++ b/.github/pull_request_template.md
@@ -17,6 +17,10 @@
 Yes | NO  
 Which branch?
 
+## Requires ChangeLog entry
+
+YES | NO - if no, why not?
+
 ## Migrations
 If there is any API change, what's the incentive and logic for it.