Update PR template

PULL_REQUEST_TEMPLATE.md

@@ -1,7 +1,15 @@
+A brief description of the changes in this PR:
+
+
 Tasks to complete before merging PR:
 - [ ]  Ensure system tests are passing. If not [Run them manually](https://github.com/0chain/zwalletcli/actions/workflows/system_tests.yml) to check for any regressions :clipboard:
 - [ ]  Do any new system tests need added to test this change? do any existing system tests need updated? If so create a PR at [0chain/system_test](https://github.com/0chain/system_test)
-- [ ]  Merge your system tests PR to master BEFORE merging this PR
+- [ ]  Merge your system tests PR to master AFTER merging this PR
 
 Associated PRs (Link as appropriate):
-...
+- blobber:
+- gosdk:
+- system_test:
+- zboxcli:
+- 0chain:
+- Other: ...