docs: add imports in some examples (#22)

* docs: add imports in some examples

* 💅

Author: hadrien

docs/pagination.md

@@ -15,7 +15,7 @@
         heading_level: false
         show_source: false
 
-### `SQLAlchemy` example
+## `SQLAlchemy` example
 
 ``` py title="example.py" hl_lines="25 26 27"
 from fastapi import FastAPI
@@ -64,7 +64,7 @@ async def list_heros(paginate: Paginate, age:int | None = None):
     return await paginate(stmt)
 ```
 
-### `SQLModel` example
+## `SQLModel` example
 
 ```python
 from fastapi import FastAPI

src/fastsqla.py

@@ -230,7 +230,10 @@ async def new_session() -> AsyncGenerator[AsyncSession, None]:
 
 Example:
 
-``` py title="example.py" hl_lines="3"
+``` py title="example.py" hl_lines="6"
+from fastsqla import Item, Session
+...
+
 @app.get("/heros/{hero_id}", response_model=Item[HeroItem])
 async def get_items(
     session: Session, # (1)!
@@ -252,6 +255,10 @@ async def get_items(
 the session instead:
 
 ```python
+from fastsqla import Item, Session
+...
+
+
 @app.post("/heros", response_model=Item[HeroItem])
 async def create_item(session: Session, new_hero: HeroBase):
     hero = Hero(**new_hero.model_dump())