Clarify repository reference in documentation

Author: nastylex

content/rest/guides/index.md

@@ -23,4 +23,4 @@ children:
 This section of the documentation is intended to get you up-and-running with
 real-world {% data variables.product.github %} API applications. We'll go over everything you need to know, from authentication to results manipulation to integrating results with other apps.
 Every tutorial will include a project, and each project will be saved and documented in our public
-[platform-samples](https://github.com/github/platform-samples) repository.
+[platform-samples](https://github.com/github/platform-samples) repository (repo).