small fixes added

readme edit and fixed one mistake in main.go file

README.md

@@ -1,14 +1,12 @@
 # CobraV2
 
-## Installation
+## Installation and compilation
 
 ```bash
 git clone https://www.github.com/foglar/cobraV2.git
-```
+cd cobraV2/serial_read
 
-```bash
 # Building serial read code yourself
-cd serial_read
 go build main.go
 ```
 

serial_read/main.go

@@ -103,8 +103,8 @@ func main() {
 			}
 			i++
 		}
-
-		if port == "" {
+		_, err := os.Stat(port)
+		if port == "" || os.IsNotExist(err) {
 			port = portInput()
 		}
 		if baudrate == 0 {