chore: add scripts to update discovery artifacts (#1286)

These PR add the scripts from #1187 that are needed to update discovery artifacts using a Github action. The scripts will be removed from #1187 once all of the review comments from #1187 have been resolved.

This PR adds the following files under the `scripts/` folder
- `README.md` to provide instructions on manually updating discovery artifacts and API reference documentation.
- `buildprbody.py` creates a summary of the changes detected in discovery artifacts and writes them to `allapis.summary`.
- `changesummary.py` creates verbose change information for each API with discovery artifact changes.
- `createcommits.sh` creates git commits for each API with discovery artifact changes or reference document changes.
- `updatediscoveryartifacts.py` is the python file that can be used to update discovery artifacts.

I also moved `describe.py` under the scripts folder and modified it to save the discovery artifacts that are fetched.

TODO:
- [x] Add tests for scripts
- [x] Address review comments in #1187
diff --git a/scripts/README.md b/scripts/README.md
new file mode 100644
index 0000000..f2b59bd
--- /dev/null
+++ b/scripts/README.md
@@ -0,0 +1,21 @@
+# Discovery Artifact Automation
+Discovery Artifacts are automatically updated using a Github Action script. This
+documentation is intended for users that need to maintain the repository.
+
+## Updating discovery artifacts locally
+
+To update discovery artifacts locally:
+1. Create a virtual environment using `pyenv virtualenv updateartifacts`
+2. Activate the virtual environment using `pyenv activate updateartifacts`
+3. Clone the repository, and `cd` into the `scripts` directory
+4. Run `pip install -r requirements.txt`
+5. Run `pip install -e ../`
+6. Run `git checkout -b update-discovery-artifacts-manual`
+7. Run `python3 updatediscoveryartifacts.py`
+8. Run `./createcommits.sh`
+9. Run `python3 buildprbody.py`
+10. Create a pull request with the changes.
+11. Copy the contents of `temp/allapis.summary` into the PR Body.
+
+## Questions
+Feel free to submit an issue!