Merge pull request #156 from hnakamur/update_installation_for_v4

Update guide installation command for v4

Author: lammel

website/content/guide.md

@@ -14,7 +14,7 @@ type = "guide"
 ### Installation
 
 ```sh
-$ go get -u github.com/labstack/echo/...
+$ go get github.com/labstack/echo/v4
 ```
 
 ### Hello, World!