add CONTRIBUTING.md with some information on creating new migrations

Author: MoralCode

CONTRIBUTING.md

@@ -0,0 +1,9 @@
+# Contributing to the ClassClock API
+
+
+Here are some things that may be helpful for maintainers or contributors
+
+
+## making changes to the schema
+If you make changes to the DB schema, generate a new migration to allow existing users to upgrade their databases. This can be done with the command `FLASK_APP=api.py pipenv run flask db migrate -m "<message>"`. Use a short, descriptive message to describe what was changed. TO upgrade, run `FLASK_APP=api.py pipenv run flask db upgrade` to update your local db to the new schema. Don't forget to also document the changes in the changelog you made to the app and which app versions are compatible with which DB versions.
+

README.md

@@ -34,4 +34,8 @@ This API has been set up to run in a docker container.
 The simplest way to run it is to:
 1. aquire the container either from a docker repository or by running `docker build . -t classclock-api` in a cloned version of this repo
 2. set up the environment variables you want per the above table
-3. use a command like `docker run -p 8000:8000 --rm -it --env-file dev.env classclock-api:latest` to run the container interactively using `dev.env` as the source of the environment variables. The app will start up on port 8000.
+3. use a command like `docker run -p 8000:8000 --rm -it --env-file dev.env classclock-api:latest` to run the container interactively using `dev.env` as the source of the environment variables. The app will start up on port 8000.
+
+## Contributing
+
+If you are interested in making changes to the ClassClock API, see the [CONTRIBUTING](./CONTRIBUTING.md) file for details on how to do so.