Doc workflow

[therzka]

This work is part of the epic that aims to document Amplify's API using the OpenAPI spec: OpenSourceFellows#125

other related issues:
OpenSourceFellows#131

This PR:

• Starts documenting Amplify's existing endpoints using the OpenAPI schema (in swagger.yaml in the root directory)
• Adds a script to locally bundle and lint the openAPI multi-file schema using Redocly-CLI
• Adds a GitHub workflow to lint schema and comment on the PR if there are changes to openapi.yml or any file in docs/bundled_api_docs
• Adds a GitHub workflow that:
  • uploads the openapi.yaml artifact
  • downloads the openapi.yaml artifact to be used in the next steps
  • generates the Swagger UI files from the OpenAPI spec
  • [not working yet] puts files onto the gh-pages branch and deploys that branch to GitHub Pages

To see how the API docs look so far (as of 04/26/2022), see https://therzka.github.io/amplify/

TODO:

• document remaining API endpoints (some are only partially filled out)
• add documentation for how to document API endpoints using swagger/openAPI
  • see https://swagger.io/docs/specification/about/
• enforce/remind about swagger.yml updates upon changing server/routes/api/* files in ways that would affect
• fix permissions for deploying docs to GitHub pages via the workflow added in this PR (see https://github.com/ProgramEquity/amplify/runs/6185163572?check_suite_focus=true)
• add a workflow step for swagger.yml schema validation (assuming the swagger-ui action doesn't already do this)

[github-actions]

Looks like you've updated the API spec! Make sure to check the output of the Lint Open API Spec`` action and make sure you've run script/lint-and-bundle-openapi-schema.sh` and have committed any resulting changes."

[github-actions]

Looks like you've updated the OpenAPI spec! Make sure to check the output of the Lint Open API Spec`` action and make sure you've run script/lint-and-bundle-openapi-schema.sh` and have committed any resulting changes.

[github-actions]

Looks like you've updated the OpenAPI spec! Make sure to:

• check the output of the Lint Open API Spec action
• run script/lint-and-bundle-openapi-schema.sh and commit any resulting changes.