Update index.md (#1544)

Fixed small typo / LB in https://developer.shopware.com/docs/resources/guidelines/testing/store/quality-guidelines-plugins/#unauthorized-file-formats-or-folders-detected-in-the-app

resources/guidelines/testing/store/quality-guidelines-plugins/index.md

@@ -506,7 +506,7 @@ Remove out-commented code, unused files and folders, and all dev-files from your
 
 Here are some examples of not allowed folders and files:
 * /__MACOSX
-*./tests
+* /tests
 * .gitignore
 * .gitkeep
 * .gitlab-ci.yml