docs: Include screenshot

Fixes #237

Author: Ed Page

README.md

@@ -6,6 +6,8 @@ Finds and corrects spelling mistakes among source code:
 - Fast enough to run on monorepos
 - Low false positives so you can run on PRs
 
+![Screenshot](./docs/screenshot.png)
+
 [![Build Status](https://dev.azure.com/crate-ci/crate-ci/_apis/build/status/typos?branchName=master)](https://dev.azure.com/crate-ci/crate-ci/_build/latest?definitionId=11&branchName=master)
 [![codecov](https://codecov.io/gh/crate-ci/typos/branch/master/graph/badge.svg)](https://codecov.io/gh/crate-ci/typos)
 [![Documentation](https://img.shields.io/badge/docs-master-blue.svg)][Documentation]