[added] Documentation for release process

Author: appsforartists

RELEASING.md

@@ -0,0 +1,32 @@
+# Releasing #
+
+To push a new build to NPM, follow these steps.  If the process changes, please update this doc. :smiley:
+
+1.  Ensure that all local changes have been uploaded to GitHub.
+2.  Verify that [continuous integration](https://circleci.com/gh/material-motion/material-motion-js) is passing.
+3.  Build each package. (`yarn run build` in the repo root.)
+    1.  Verify there are no build/lint warnings.  If there are, fix them, and go back to step 1.
+    2.  Smoke test `demos-react`.
+        -   `yarn run serve` it, and ensure the interactions all work as expected.
+    2.  Smoke test them in a separate project that uses Material Motion.
+        1.  Replace the project's copy of the `material-motion` packages with the built artifacts.
+        2.  Serve the project, and ensure the interactions still work as expected.
+3.  Read each README, and ensure its information is current.
+4.  Verify that each package's `.npmignore` is correct.
+5.  Update the version number:
+    -   In `lerna.json`.
+    -   In each package's README:
+        -   In the NPM badge.
+        -   In the `<script>` tag example, if there is one.
+6.  Update the CHANGELOG.
+7.  Commit the README and CHANGELOG updates as `[release] v#.#.#`, and upload the commit.
+8. `lerna publish`
+9.  `yarn run deploy` in `demos-react`.  Check that http://material-motion-demos.firebaseapp.com still works correctly.
+10. Delete the `material-motion` packages in the test project and run `yarn` again to pull the published version from NPM.  Smoke test it again to validate that the deployed version works correctly.
+11. Look at the published packages on [npmjs.com](https://www.npmjs.com/package/material-motion), and verify the versions and READMEs look correct.
+12. Update the `stable` branch:
+    ```
+    git checkout stable
+    git reset --hard develop
+    git push origin stable
+    ```