doc: remove lgtm badge (#20)

Author: bubkoo

README.md

@@ -8,7 +8,6 @@
   <a href="https://www.typescriptlang.org" rel="nofollow"><img alt="Language" src="https://img.shields.io/badge/language-TypeScript-blue.svg?style=flat-square"></a>
   <a href="https://github.com/wow-actions/use-app-token/pulls"><img alt="PRs Welcome" src="https://img.shields.io/badge/PRs-Welcome-brightgreen.svg?style=flat-square" ></a>
   <a href="https://github.com/marketplace/actions/use-app-token" rel="nofollow"><img alt="website" src="https://img.shields.io/static/v1?label=&labelColor=505050&message=Marketplace&color=0076D6&style=flat-square&logo=google-chrome&logoColor=0076D6" ></a>
-  <a href="https://lgtm.com/projects/g/wow-actions/use-app-token/context:javascript" rel="nofollow"><img alt="Language grade: JavaScript" src="https://img.shields.io/lgtm/grade/javascript/g/wow-actions/use-app-token.svg?logo=lgtm&style=flat-square" ></a>
 </p>
 
 This GitHub Action can be used to **impersonate** a GitHub App when `secrets.GITHUB_TOKEN`'s limitations are too restrictive and a personal access token is not suitable. [`secrets.GITHUB_TOKEN`](https://help.github.com/en/actions/configuring-and-managing-workflows/authenticating-with-the-github_token) has limitations such as [not being able to triggering a new workflow from another workflow](https://github.community/t5/GitHub-Actions/Triggering-a-new-workflow-from-another-workflow/td-p/31676). A workaround is to use a [personal access token](https://help.github.com/en/github/authenticating-to-github/creating-a-personal-access-token-for-the-command-line) from a [personal user/bot account](https://help.github.com/en/github/getting-started-with-github/types-of-github-accounts#personal-user-accounts). However, for organizations, GitHub Apps are [a more appropriate automation solution](https://developer.github.com/apps/differences-between-apps/#machine-vs-bot-accounts).