changed go get to go install to install swag cli (#15)

Author: SahilDhingraa

README.md

@@ -15,7 +15,7 @@ fiber middleware to automatically generate RESTful API documentation with Swagge
 2. Download [Swag](https://github.com/swaggo/swag) for Go by using:
 
 ```sh
-$ go get github.com/swaggo/swag/cmd/swag
+$ go install github.com/swaggo/swag/cmd/swag
 ```
 
 3. Run the [Swag](https://github.com/swaggo/swag) in your Go project root folder which contains `main.go` file, [Swag](https://github.com/swaggo/swag) will parse comments and generate required files(`docs` folder and `docs/doc.go`).