Enhance credential prompt to use server address from config

README.md

@@ -76,8 +76,11 @@ $ alpacon login
 
 $ alpacon login -s [SERVER URL] -u [USERNAME] -p [PASSWORD]
 ```
-Successful login creates `config.json` in `~/.alpacon`, containing server address, API token, and token expiration (~1 week).
-This file is essential for command execution and a new login is required upon token expiration.
+A successful login generates a `config.json` file in `~/.alpacon`, which includes the server address, API token, and token expiration time (approximately 1 week). 
+This file is crucial for executing commands, and you will need to log in again once the token expires.
+
+Upon re-login, the Alpacon CLI will automatically reuse the server address from `config.json`, unless you provide all the flags (-s, -u, -p). 
+If you need to connect to a different server or change the server address, you can either directly modify the `config.json` file in ~/.alpacon or provide all flags to specify a new server URL.
 
 #### Default Server URL
 If you do not explicitly specify the server URL (-s) in the command, the default value `https://alpacon.io` is used. 

cmd/login.go

@@ -47,7 +47,7 @@ func promptForCredentials() {
 	configFile, err := config.LoadConfig()
 	if err == nil && configFile.ServerAddress != "" {
 		loginRequest.ServerAddress = configFile.ServerAddress
-		fmt.Println("Using server address from config:", configFile.ServerAddress, ". To modify it, edit `~/.alpacon/config.json`")
+		fmt.Println("Using server address from config:", configFile.ServerAddress, ". Modify it in `~/.alpacon/config.json` or use all flags (-s, -u, -p) for changes.")
 	} else {
 		loginRequest.ServerAddress = utils.PromptForInput("Server Address[https://alpacon.io]: ")
 		if loginRequest.ServerAddress == "" {