Add documentation for the release process (NREL#727)

docs/dev_guide.md

@@ -224,6 +224,70 @@ jupyter-book build docs/
 open docs/_build/html/index.html
 ```
 
+## Release guide
+
+Follow the process outlined here to "release" FLORIS.
+After completing these steps, a few additional automated processes
+are launched to deploy FLORIS to PyPI and conda-forge.
+Be sure to complete each step in the sequence as described.
+
+1. Merge the `develop` branch into `main` with a pull request.
+    Create a pull request titled `FLORIS vN.M` with version number filled in
+    as appropriate.
+    The body of the pull request should a brief summary of the changes
+    as well as a listing of the major changes and their associated pull requests.
+    Since creating the pull request does not mean it is merged, it is
+    reasonable to create the pull request, and edit the body of the pull
+    request later.
+    The pull request template has a checklist at the bottom that should be
+    uncommented for this PR.
+
+2. Update the version number and commit to the `develop`` branch
+    with a commit message such as "Update version to vN.M".
+    The version number must be updated in the following two files:
+    - [floris/README.md](https://github.com/NREL/floris/blob/main/README.md)
+    - [floris/floris/version.py](https://github.com/NREL/floris/blob/main/floris/version.py)
+    Note that a `.0` version number is left off meaning that valid versions
+    are `v3`, `v3.1`, `v3.1.1`, etc.
+
+3. Verify that the documentation is building correctly.
+    The docs build for every commit to `develop`, so there should be no
+    surprises in this regard prior to a release. However, it's a good
+    opportunity to ensure that the documentation is up to date and there
+    are no obvious issues.
+    Check this by opening the documentation website at https://nrel.github.io/floris/intro.html
+    and scrolling through the pages.
+    Also, verify that the automated build process has successfully completed
+    for the commits to `develop` in [GitHub Actions](https://github.com/NREL/floris/actions/workflows/deploy-pages.yaml).
+
+4. The changes since the prior commit can be gotten from GitHub by going through the
+    process to create a release, but stopping short of actually publishing it.
+    In this form, GitHub provides the option to autogenerate release notes.
+    Be sure to choose the correct starting tag, and then hit "Generate release notes".
+    Then, copy the generated text into the pull request body, and format it
+    as appropriate. A good reference is typically the previous release.
+
+5. Merge the pull request into `main`. Select "Create a merge commit" from the merge
+    dropdown, and hit "Merge pull request".
+
+6. Create a [new release](https://github.com/NREL/floris/releases/new) on GitHub
+    with the title "vN.M". Choose to create a new tag on publish with the same
+    name. Also, autogenerate the release notes again. If you autogenerated the release
+    notes in step 4, make sure to start this step from a new browser window.
+    Be sure that the "Set as latest release" radio button is enabled.
+
+7. Double check everything.
+
+8. Hit "Publish release".
+
+9. Go to GitHub Actions and watch the [Upload Python Package](https://github.com/NREL/floris/actions/workflows/python-publish.yml)
+    job complete. Upon success, FLORIS will be uploaded to PyPI for installation with pip.
+    If it fails, the latest release will not be distributed.
+
+10. Merge the main branch into develop to align all branches on all remotes.
+
+11. That's it, well done!
+
 ## Deploying to pip
 
 Generally, only NREL developers will have appropriate permissions to deploy