update README

Author: stepbystepcode

.DS_Store

@@ -0,0 +1,95 @@
+# API Documentation
+## User Management
+```POST /api/signup```
+
+Register a new user account.
+
+- Request Body:
+
+username: Username string
+password: Password string
+other user info fields
+- Response:
+
+201: User created successfully
+409: Username already exists
+
+```POST /api/login```
+
+Login with username and password.
+
+- Request Body:
+
+username: Username string
+password: Password string
+- Response:
+
+200: Login succeeded
+401: Invalid credentials
+Chat
+
+```POST /api/chat```
+
+Send a chat message.
+
+- Request Body:
+
+content: Chat message content
+userId: Sender user ID
+roomId: Chat room ID
+- Response:
+
+200: Message sent
+404: User or chat room not found
+Friend Management
+POST /api/nfmgr
+Manage friend requests.
+
+- Request Body:
+
+action: add to send request, accept to accept request
+userId: Recipient user ID
+- Response:
+
+200: Request success
+404: User not found
+GET /api/newfriends
+Get list of pending friend requests.
+
+- Response:
+200: Array of friend request objects
+401: Unauthorized
+User Info
+GET /api/info
+Get user profile information.
+
+- Request Header:
+
+Authorization: JWT token
+- Response:
+
+200: User info object
+401: Invalid token
+File Management
+POST /api/file/save
+Save a file.
+
+- Request Body:
+
+file: File data
+path: File path
+filename: Filename
+- Response:
+
+201: File saved
+500: Error saving file
+GET /api/file/get
+Get a file.
+
+- Request Parameter:
+
+filePath: Path of file on server
+Response:
+
+200: File data
+404: File not found