add section to setup.md on how to apply migrations

SETUP.md

@@ -3,6 +3,7 @@
 ## Table of Contents
 1. [Prerequisites](#prerequisites)
 2. [Setup](#setup)
+3. [Applying Migrations](#applying-migrations)
 
 ---
 
@@ -26,3 +27,31 @@ this starts all the containers however you can just remove them as you like. If
 ```bash
 docker compose -f dev-compose.yml down
 ```
+
+# Applying Migrations
+If migrations haven't been applied yet you can apply them with the following commands:
+
+*Note: Plase ensure the database is running*
+
+1. remove old docker image to rebuild
+```bash
+docker image remove apfelnetzwerk-backend
+```
+
+2. check which dockers are running
+```bash
+docker ps
+```
+
+3. attach a shell to the running postgres docker container
+```bash
+docker exec -it <it/name> /bin/bash
+```
+
+4. apply migrations
+```bash
+#(go into the crates folder)
+cd crates
+#run migrations
+sea-orm-cli migrate fresh 
+```