📝 Add first tutorial src files

docs/tutorial/src/tutorial16.py

@@ -0,0 +1,15 @@
+from fastapi import FastAPI, Query
+
+app = FastAPI()
+
+
+@app.get("/items/")
+async def read_items(
+    q: str = Query(
+        None, title="Query string", min_length=3, max_length=50, regex="^fixedquery$"
+    )
+):
+    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
+    if q:
+        results.update({"q": q})
+    return results