What are some alternatives?
When comparing ReadMe and Atlassian Bitbucket Server, you can also consider the following products
GitBook - Modern Publishing, Simply taking your books from ideas to finished, polished books.
Visual Studio Team Services - Visual Studio Team Services (VSTS) provides unlimited Git hosting, cloud build for CI, agile planning and continuous delivery.
ReadTheDocs - Spend your time on writing high quality documentation, not on the tools to make your documentation work.
GitHub Desktop - GitHub Desktop is a seamless way to contribute to projects on GitHub and GitHub Enterprise.
Docusaurus - Easy to maintain open source documentation websites
Mercurial SCM - Mercurial is a free, distributed source control management tool.