docs: use "go install" with latest commit

Author: hekmekk

docs/installation.md

@@ -13,10 +13,17 @@
 ## Install git-team
 ### Golang
 For releases since v1.6.0.
-```shell script
+
+Install the latest stable release.
+```shell
 go install github.com/hekmekk/git-team@latest
 ```
 
+Install from the latest commit.
+```shell
+go install github.com/hekmekk/git-team@HEAD
+```
+
 ### Homebrew
 See [homebrew-git-team](https://github.com/hekmekk/homebrew-git-team) for the formula.
 1. Add tap