how to install spotless git hook (getsentry/sentry-android#128)

CONTRIBUTING.md

@@ -4,6 +4,12 @@ We love pull requests from everyone.
 
 The project currently requires you run JDK version `1.8.x`.
 
+To install spotlessCheck pre-commit hook:
+
+```shell
+git config core.hooksPath hooks/
+```
+
 To run the build and tests:
 
 ```shell

hooks/pre-commit

@@ -0,0 +1,13 @@
+#!/bin/sh
+# From gist at https://gist.github.com/chadmaughan/5889802
+
+echo '[git hook] executing gradle spotlessCheck before commit'
+
+# run the spotlessCheck with the gradle wrapper
+./gradlew spotlessCheck --daemon
+
+# store the last exit code in a variable
+RESULT=$?
+
+# return the './gradlew spotlessCheck' exit code
+exit $RESULT