Update README to include database migration instructions

README.md

@@ -17,10 +17,30 @@ To simplify development, all local infrastructure is handled with Docker. The fo
 
 - `compose.yaml`: A Docker compose file that stands up a Postgres database and a pgAdmin instance to visualize.
 
+### Database Migrations
+
+Any time a change is made to a `.entity.ts` file, a new migration will need to be generated and added to the `appDataSource.ts` file. This ensures the API is refencing the most up-to-date (and valid!) database schema. These are the migration commands:
+
+```bash
+# generate migration
+$ npm run db:gen_migration
+
+# generate migration with a custom name
+$ npm run db:gen_migration_named --name=<any_name_here>
+
+# show migrations
+$ npm run db:show_migrations
+
+# run migrations
+$ npm run db:run_migrations
+```
+
+**NOTE ON MIGRATIONS IN TYPEORM**: In order for any new migration to be considered in the `db:show_migrations` or `db:run_migrations` commands, they'll need to be added to the `appDataSource.ts` file, under the `migrations: []` option.
+
 ## Compile and run the project
 
 ```bash
-# Set env variables
+# Set env variables, which default to local infrastructure
 $ . ./set-env
 
 # development