Merge pull request #3980 from shaedrich/documentation

Add related to topic "Documentation"

Author: ahpook

topics/documentation/index.md

@@ -5,5 +5,6 @@ short_description: Documentation is a set of information that describes a produc
   to its users.
 topic: documentation
 wikipedia_url: https://en.wikipedia.org/wiki/Software_documentation
+related: tutorial, man-page, documentation-as-code, docblock, doc-gen, api-documentation, knowledge-base, design-document
 ---
 Documentation is a set of information that describes a product to its users, including what it is, how it operates, and how to use it.