prevent this error labstack/echo#1374 (#177)

* Improve installation section to avoid errors like `https://github.com/labstack/echo/issues/1374`

Co-authored-by: Roland Lammel <[email protected]>

website/content/guide.md

@@ -13,16 +13,22 @@ type = "guide"
 
 ### Installation
 
+To install Echo Go v1.13 or higher is required. Go v1.12 has limited support and some middlewares will not be available.
+Make sure your project folder is outside your `$GOPATH`.
+
 ```sh
+$ mkdir myapp && cd myapp
+$ go mod init myapp
 $ go get github.com/labstack/echo/v4
 ```
 
-If you are working with a Go v1.14 or earlier use:
+If you are working with Go v1.14 or earlier use:
 
 ```sh
 $ GO111MODULE=on go get github.com/labstack/echo/v4
 ```
 
+
 ### Hello, World!
 
 Create `server.go`