📝 Add builtin section; add ohmyapi_auth docs

docs/auth.md

@@ -0,0 +1,45 @@
+# Authentication
+
+OhMyAPI comes bundled with a builtin authentication app.
+Simply add `ohmyapi_auth` to your `INSTALLED_APPS` and configure a `JWT_SECRET`.
+
+## Enable Auth App
+
+`settings.py`:
+
+```
+INSTALLED_APPS = [
+    "ohmyapi_auth",
+    ...
+]
+
+JWT_SECRET = "t0ps3cr3t"
+```
+
+Remember to `makemigrations` and `migrate` to create the necessary database tables.
+
+```
+ohmyapi makemigrations
+ohmyapi migrate
+```
+
+## Permissions
+
+With the `ohmyapi_auth` app comes everything you need to implement API-level permissions.
+Use FastAPI's `Depends` pattern in combination with either the provided or custom permissions.
+
+```python
+from ohmyapi.router import APIRouter, Depends
+
+from ohmyapi_auth import (
+    models as auth,
+    permissions,
+)
+
+router = APIRouter()
+
+
+@router.get("/")
+def get(user: auth.User = Depends(permissions.required_authenticated)):
+    ...
+```