chore(go): add pre-commit hook (#1006)

* chore(go): add pre-commit hook
run go mod tidy
add description

* use bash

* adjust indentation

* fix code climate issue

* docs: clarify git hook usage description

* Update .hooks/README.md

.hooks/README.md

@@ -0,0 +1,33 @@
+# Git Hooks
+
+From [Git docs](https://git-scm.com/docs/githooks#_description):
+
+> Hooks are programs you can place in a hooks directory to trigger actions at certain points in git’s execution. Hooks that don’t have the executable bit set are ignored.
+
+## Usage
+
+To use the hook, execute this command in the project root directory to link the script into the `.git/hooks` directory:
+
+```sh
+ln -s -f ../../.hooks/pre-commit ./.git/hooks/pre-commit
+```
+
+Make sure the file is executable:
+
+```sh
+chmod +x ./.hooks/pre-commit
+```
+
+## Pre-Commit Hook
+
+From [Git docs](https://git-scm.com/docs/githooks#_pre_commit):
+
+> This hook is invoked by git-commit, and can be bypassed with the --no-verify option. It takes no parameters, and is invoked before obtaining the proposed commit log message and making a commit. Exiting with a non-zero status from this script causes the git commit command to abort before creating a commit.
+
+### Content
+
+Executes `go mod tidy` and stages `go.mod` & `go.sum`.
+
+From [Golang docs](https://github.com/golang/go/wiki/Modules):
+
+> `go mod tidy` — Prune any no-longer-needed dependencies from `go.mod` and add any dependencies needed for other combinations of OS, architecture, and build tags (details).

.hooks/pre-commit

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+STAGED_GO_FILES=$(git diff --staged --name-only | grep "\.go$")
+
+if [[ "$STAGED_GO_FILES" = "" ]]; then
+    exit 0
+fi
+
+echo "cleaning GO dependencies"
+go mod tidy
+git add go.mod go.sum