no more home bin, add script package to PATH

internal/update-git-prompt.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+
+# the command used to initialize our partial subtree
+#git remote add -f -t master --no-tags gitprompt https://github.com/git/git.git
+#git read-tree --prefix=git-prompt/ -u gitprompt/master:contrib/completion
+#git commit
+
+# the command used to update our partial subtree
+git rm -rf git-prompt
+git read-tree --prefix=git-prompt/ -u gitprompt/master:contrib/completion
+git commit
+