added FastApi Doc

Docs/Services/FastAPI/03-Get-Post-Json.md

@@ -0,0 +1,27 @@
+```python
+
+from fastapi import FastAPI
+
+app = FastAPI()
+
+users = [
+    {'name': 'abbas ' , 'age': '20'},
+    {'name': 'mmd ' , 'age': '37'},
+    {'name': 'asghar ' , 'age': '19'}
+]
+
+@app.get("/")
+def root_dir:
+    return {'message' , 'api is working'}
+
+@app.get("/users")
+def home_dir():
+    return users
+
+@app.get("/user/{name_input}")
+def read_item(name_input: str):
+   for item in users:
+        if item["name"] == name_input:
+            return {"information": item}
+    return {"message" , "not worked"}
+```