readme: Improve readme

.github/workflows/test.yml

@@ -0,0 +1,18 @@
+on: [push, pull_request]
+name: Test
+jobs:
+  test:
+    strategy:
+      matrix:
+        go-version: [1.15.x, 1.16.x]
+        os: [macos-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+    - name: Install Go
+      uses: actions/setup-go@v2
+      with:
+        go-version: ${{ matrix.go-version }}
+    - name: Check out code
+      uses: actions/checkout@v2
+    - name: Test
+      run: go test -race ./...

README.md

@@ -1,3 +1,29 @@
 # clocks
 
-Command clocks places additional time zones into your mac status bar.
+[![Project status](https://img.shields.io/github/release/tmc/clocks.svg?style=flat-square)](https://github.com/tmc/clocks/releases/latest)
+[![Build Status](https://github.com/tmc/clocks/workflows/Test/badge.svg)](https://github.com/tmc/clocks/actions?query=workflow%3ATest)
+[![Go Report Card](https://goreportcard.com/badge/tmc/clocks?cache=0)](https://goreportcard.com/report/tmc/clocks)
+[![go.dev reference](https://img.shields.io/badge/go.dev-reference-007d9c?logo=go&logoColor=white&style=flat-square)](https://pkg.go.dev/github.com/tmc/clocks)
+
+Command clocks places additional time zones into your Mac status bar.
+
+## Installation
+
+clocks is a [Go](https://golang.org/) program for MacOS systems.
+
+## Usage
+
+```console
+$ clocks -h
+Usage of clocks:
+  -fmt string
+    	time format string (golang time pkg) (default "Mon Jan 2 15:04 MST")
+  -tzs string
+    	time zones (default "UTC,America/Los_Angeles")
+```
+
+## Example Output
+
+This is example output from running `clocks`:
+
+![example output](./docs/example-statusbar-image.png)