What are some alternatives?
When comparing ReadMe and Visual Studio Team Services, you can also consider the following products
GitBook - Modern Publishing, Simply taking your books from ideas to finished, polished books.
Helix ALM - Helix ALM is the single, integrated application that lets you centralize and manage requirements, test cases, issues, and other development artifacts and their relationships.
ReadTheDocs - Spend your time on writing high quality documentation, not on the tools to make your documentation work.
codeBeamer ALM - Integrated application lifecycle management (ALM) platform
Docusaurus - Easy to maintain open source documentation websites
Atlassian Bitbucket Server - Atlassian Bitbucket Server is a scalable collaborative Git solution.