Merge PR #2041: Update PR template for release process

.github/PULL_REQUEST_TEMPLATE.md

@@ -4,6 +4,8 @@ v    Before smashing the submit button please review the checkboxes.
 v    If a checkbox is n/a - please still include it but + a little note why
 ☺ > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >  -->
 
+- Targeted PR against correct branch (see [CONTRIBUTING.md](https://github.com/cosmos/cosmos-sdk/blob/develop/CONTRIBUTING.md#pr-targeting))
+
 - [ ] Linked to github-issue with discussion and accepted design OR link to spec that describes this work.
 - [ ] Wrote tests
 - [ ] Updated relevant documentation (`docs/`)

CONTRIBUTING.md

@@ -133,6 +133,17 @@ Libraries need not follow the model strictly, but would be wise to.
 
 The SDK utilizes [semantic versioning](https://semver.org/).
 
+### PR Targeting
+
+Ensure that you base and target your PR on the correct branch:
+  - `release/vxx.yy.zz` for a merge into a release candidate
+  - `master` for a merge of a release
+  - `develop` in the usual case
+
+All feature additions should be targeted against `develop`. Bug fixes for an outstanding release candidate
+should be targeted against the release candidate branch. Release candidate branches themselves should be the
+only pull requests targeted directly against master.
+
 ### Development Procedure:
   - the latest state of development is on `develop`
   - `develop` must never fail `make test` or `make test_cli`