Add release checklist (#1316)

* Add release checklist

* add space to checkbox

* polkadot-js-apps

* Apply suggestions from code review

Co-authored-by: joe petrowski <25483142+joepetrowski@users.noreply.github.com>

* add notes for each release item

* Apply suggestions from code review

Co-authored-by: s3krit <pugh@s3kr.it>

* Apply suggestions from code review

Co-authored-by: Pierre Krieger <pierre.krieger1708@gmail.com>
Co-authored-by: Gavin Wood <gavin@parity.io>

* Update RELEASE.md

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update RELEASE.md - rearrange sections

Co-authored-by: joe petrowski <25483142+joepetrowski@users.noreply.github.com>
Co-authored-by: joepetrowski <joe@parity.io>
Co-authored-by: s3krit <pugh@s3kr.it>
Co-authored-by: Pierre Krieger <pierre.krieger1708@gmail.com>
Co-authored-by: Gavin Wood <gavin@parity.io>
Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

RELEASE.md

+# Release Checklist
+
+The following checks should be completed before publishing a new release of the
+Polkadot/Kusama/Westend runtime or client.
+
+### Runtime Releases
+
+The following should be done *prior* to tagging the potential release. Upon
+completion, tag the commit and proceed with the [All Releases](#all-releases) steps.
+
+- [ ] List any [native runtime](#native-runtimes) versions associated with the release.
+- [ ] Has incremented  [`spec_version`](#spec-version) for any native runtimes from any existing use on public (non-private/test) networks.
+- [ ] Verify [new migrations](#new-migrations) complete successfully, and the runtime state is
+  correctly updated.
+- [ ] Verify previously [completed migrations](#old-migrations-removed) are removed.
+- [ ] Verify pallet and [extrinsic ordering](#extrinsic-ordering) has stayed the same. Bump
+  `transaction_version` if not.
+- [ ] Verify new extrinsics have been correctly whitelisted/blacklisted for
+  [proxy filters](#proxy-filtering).
+- [ ] Verify [benchmarks](#benchmarks) have been updated for any modified runtime logic.
+- [ ] Verify [Polkadot JS API](#polkadot-js) are up to date with the latest runtime changes.
+
+### All Releases
+
+- [ ] Check that the new client versions have [run on the network](#burn-in) without issue for 12
+  hours.
+- [ ] Check that a draft release has been created at https://github.com/paritytech/polkadot/releases with relevant [release notes](#release-notes)
+- [ ] Check that [build artifacts](#build-artifacts) have been added to the draft-release
+
+## Notes
+
+### Burn In
+
+Ensure that Parity DevOps has run the new release on Westend, Kusama, and Polkadot validators for
+at least 12 hours prior to publishing the release.
+
+### Build Artifacts
+
+Add any necessary assets to the release. They should include:
+
+- Linux binary
+- GPG signature of the Linux binary
+- SHA256 of binary
+- Source code
+- Wasm binaries of any runtimes
+
+### Release notes
+
+The release notes should list:
+
+- The priority of the release (i.e., how quickly users should upgrade)
+- Which native runtimes and their versions are included
+- The proposal hashes of the runtimes as built with [srtool](https://gitlab.com/chevdor/srtool)
+
+The release notes may also list:
+
+- Free text at the beginning of the notes mentioning anything important regarding this release
+- Notable changes (those labelled with B[1-9]-* labels) separated into sections
+
+### Spec Version
+
+A runtime upgrade must bump the spec number. This may follow a pattern with the client release
+(e.g. runtime v12 corresponds to v0.8.12, even if the current runtime is not v11).
+
+### New Migrations
+
+Ensure that any migrations that are required due to storage or logic changes are included in the
+`on_runtime_upgrade` function of the appropriate pallets.
+
+### Old Migrations Removed
+
+Any previous `on_runtime_upgrade` functions from old upgrades must be removed to prevent them from
+executing a second time.
+
+### Extrinsic Ordering
+
+Offline signing libraries depend on a consistent ordering of call indices and functions. Compare
+the metadata of the current and new runtimes and ensure that the `module index, call index` tuples
+map to the same set of functions. In case of a breaking change, increase `transaction_version`.
+
+Note: Adding new functions to the runtime does not constitute a breaking change as long as they are
+added to the end of a pallet (i.e., does not break any other call index).
+
+### Proxy Filtering
+
+The runtime contains proxy filters that map proxy types to allowable calls. If the new runtime
+contains any new calls, verify that the proxy filters are up to date to include them.
+
+### Benchmarks
+
+Run the benchmarking suite with the new runtime and update any function weights if necessary.
+
+### Polkadot JS
+
+Ensure that a release of [Polkadot JS API]() contains any new types or interfaces necessary to
+interact with the new runtime.