docs: add "used by" badge

EndBug · EndBug · commit 9650af1f95c8 · 2020-08-05T12:09:59.000+02:00
diff --git a/README.md b/README.md
@@ -1,4 +1,5 @@
 # Add & Commit
+[![Used by](https://img.shields.io/endpoint?url=https%3A%2F%2Fapi-git-master.endbug.vercel.app%2Fapi%2Fgithub-actions%2Fused-by%3Faction%3DEndBug%2Fadd-and-commit%26badge%3Dtrue)](https://github.com/search?o=desc&q=EndBug%2Fadd-and-commit+path%3A.github%2Fworkflows+language%3AYAML&s=&type=Code)
 [![All Contributors](https://img.shields.io/badge/all_contributors-14-orange.svg?style=flat)](#contributors-)
 
 You can use this GitHub Action to commit changes made in your workflow run directly to your repo: for example, you use it to lint your code, update documentation, commit updated builds, etc....

Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,5 @@`
`1`	`1`	`# Add & Commit`
	`2`	`+[![Used by](https://img.shields.io/endpoint?url=https%3A%2F%2Fapi-git-master.endbug.vercel.app%2Fapi%2Fgithub-actions%2Fused-by%3Faction%3DEndBug%2Fadd-and-commit%26badge%3Dtrue)](https://github.com/search?o=desc&q=EndBug%2Fadd-and-commit+path%3A.github%2Fworkflows+language%3AYAML&s=&type=Code)`
`2`	`3`	`[![All Contributors](https://img.shields.io/badge/all_contributors-14-orange.svg?style=flat)](#contributors-)`
`3`	`4`
`4`	`5`	`You can use this GitHub Action to commit changes made in your workflow run directly to your repo: for example, you use it to lint your code, update documentation, commit updated builds, etc....`