[website] Add function to save on WebAPIs (#493)

* add which function to keep in WebAPIs

* add root function

* update flaskapi and fastapi docs

Author: inaki321

website/learn/code/deployment.md

@@ -42,22 +42,55 @@ hal9 deploy webapp --type streamlit
 
 Web APIs are applications that are designed for other computer programs or services to interoperate with, if you wanted to enable other web apps to use your previous app, you would do this as follows:
 
+Always ensure any API's root path `@app.get("/")` function is kept, because Hal9 Web APIs use this endpoint to check the application's status.
+
+Hal9 is able to run Python FastAPI or Flask apps.
+
+### Fast API
 ```python deploy
 from fastapi import FastAPI
 import random
 
 app = FastAPI()
 
 @app.get("/")
+def read_root():
+    return {"success": True}
+
+@app.get("/roll")
 async def roll():
     return f"You rolled a {random.randint(1, 6)}!"
 ```
 
+### Flask API
+```python deploy
+from flask import Flask, jsonify, request
+from asgiref.wsgi import WsgiToAsgi # WSGI compatible with Hal9 launcher
+import random
+
+flaskapp = Flask(__name__)
+
+@flaskapp.route("/", methods=['GET'])
+def read_root():
+    return jsonify({"success": True})
+
+@flaskapp.route("/roll", methods=['GET'])
+def roll():
+  return f"You rolled a {random.randint(1, 6)}!"
+
+app = WsgiToAsgi(flaskapp)
+```
+
 When a chatbot generates an API, Hal9 automatically deploys and embeds the API endpoint; however, if you have to manually deploy an API you can accomplish this as follows:
 
 ```bash
 pip install hal9
 
+# flask api app creation
 hal9 create webapi --type flask
 hal9 deploy webapi --type flask
+
+# fast api app creation
+hal9 create webapi --type fastapi
+hal9 deploy webapi --type fastapi
 ```