feat(private-key): escaped newlines will be replaced (#132)

via https://github.com/gr2m/universal-github-app-jwt/releases/tag/v2.1.1

Author: dependabot[bot]

README.md

@@ -211,7 +211,7 @@ jobs:
 
 ### `private-key`
 
-**Required:** GitHub App private key.
+**Required:** GitHub App private key. Escaped newlines (`\\n`) will be automatically replaced with actual newlines.
 
 ### `owner`