Add release checklist

RELEASING.md

@@ -0,0 +1,65 @@
+# Release Checklist
+
+These steps assume that you've checked out the Subxt repository and are in the root directory of it.
+
+We also assume that ongoing work done is being merged directly to the `master` branch.
+
+1.  Ensure that everything you'd like to see released is on the `master` branch.
+
+2.  Create a release branch off `master`, for example `release-v0.17.0`. Decide how far the version needs to be bumped based
+    on the changes to date. If unsure what to bump the version to (e.g. is it a major, minor or patch release), check with the
+    Parity Tools team.
+
+3.  Check that you're happy with the current documentation.
+
+    ```
+    cargo doc --open --all-features
+    ```
+
+    CI checks for broken internal links at the moment. Optionally you can also confirm that any external links
+    are still valid like so:
+
+    ```
+    cargo install cargo-deadlinks
+    cargo deadlinks --check-http -- --all-features
+    ```
+
+    If there are minor issues with the documentation, they can be fixed in the release branch.
+
+4.  Bump the crate version in `Cargo.toml` to whatever was decided in step 2.
+
+5.  Update `CHANGELOG.md` to reflect the difference between this release and last. If you're unsure of
+    what to add, check with the Tools team. See the `CHANGELOG.md` file for details of the format it follows.
+
+    Any [closed PRs](https://github.com/paritytech/subxt/pulls?q=is%3Apr+is%3Aclosed) between the last release and
+    this release branch should be noted.
+
+6.  Commit any of the above changes to the release branch and open a PR in GitHub with a base of `master`.
+
+7.  Once the branch has been reviewed and passes CI, merge it.
+
+8.  Now, we're ready to publish the release to crates.io.
+
+    Checkout `master`, ensuring we're looking at that latest merge (`git pull`).
+
+    Next, do a dry run to make sure that things seem sane:
+    ```
+    cargo publish --dry-run
+    ```
+
+    If we're happy with everything, proceed with the release:
+    ```
+    cargo publish
+    ```
+
+9.  If the release was successful, then tag the commit that we released in the `master` branch with the
+    version that we just released, for example:
+
+    ```
+    git tag v0.17.0 # use the version number you've just published to crates.io, not this one
+    git push --tags
+    ```
+
+    Once this is pushed, go along to [the releases page on GitHub](https://github.com/paritytech/subxt/releases)
+    and draft a new release which points to the tag you just pushed to `master` above. Copy the changelog comments
+    for the current release into the release description.