Fix provided port in docs (#1652)

The port in the docker compose seems to be 8400, however the docs say
it's 3000. Users may not know why they are seeing Connection refused
issues

Author: ByteAfterlife

docs/content/running-bracket/quickstart.mdx

@@ -14,7 +14,7 @@ sudo docker compose up -d
 ```
 
 This will start the backend and frontend of Bracket, as well as a postgres instance. You should now
-be able to view bracket at `http://localhost:3000`. You can log in with the following credentials:
+be able to view bracket at `http://localhost:8400`. You can log in with the following credentials:
 
 - Username: `test@example.org`
 - Password: `aeGhoe1ahng2Aezai0Dei6Aih6dieHoo`.