message: docs: update code coverage badge
  We just added support for runing code-cov bot on our PRs and CI builds so it makes sense to update our code coverage badge from Azure Dev Ops to codecov.
diff: @@ -6,7 +6,7 @@ Licensed under the MIT License.
  ## ![Product Logo](./src/icons/brand/blue/brand-blue-48px.png) Accessibility Insights for Web
  [![Build Status](https://dev.azure.com/ms/accessibility-insights-web/_apis/build/status/AccessibilityInsights-Web-CI?branchName=master)](https://dev.azure.com/ms/accessibility-insights-web/_build/latest?definitionId=63&branchName=master)
  -[![Azure DevOps coverage](https://img.shields.io/azure-devops/coverage/ms/accessibility-insights-web/63.svg)](https://dev.azure.com/ms/accessibility-insights-web/_build?definitionId=63&_a=summary)
  +[![codecov](https://codecov.io/gh/microsoft/accessibility-insights-web/branch/master/graph/badge.svg)](https://codecov.io/gh/microsoft/accessibility-insights-web)
  [![Chrome Web Store](https://img.shields.io/chrome-web-store/v/pbjjkligggfmakdaogkfomddhfmpjeni.svg?label=Version)](https://chrome.google.com/webstore/detail/accessibility-insights-fo/pbjjkligggfmakdaogkfomddhfmpjeni)
  [![Chrome Web Store](https://img.shields.io/chrome-web-store/users/pbjjkligggfmakdaogkfomddhfmpjeni.svg)](https://chrome.google.com/webstore/detail/accessibility-insights-fo/pbjjkligggfmakdaogkfomddhfmpjeni)
  [![Chrome Web Store](https://img.shields.io/chrome-web-store/stars/pbjjkligggfmakdaogkfomddhfmpjeni.svg)](https://chrome.google.com/webstore/detail/accessibility-insights-fo/pbjjkligggfmakdaogkfomddhfmpjeni/reviews)
  