What are some alternatives?
When comparing MkDocs and ReadTheDocs, you can also consider the following products
GitBook - Modern Publishing, Simply taking your books from ideas to finished, polished books.
Sphinx Search - Sphinx is an open source full text search server, designed with performance, relevance (search quality), and integration simplicity in mind. Sphinx lets you either batch index and search data stored in files, an SQL database, NoSQL storage.
Doxygen - Doxygen is a tool for generating documentation from annotated C++ sources, as well as other popular...
Daux.io - Daux.io is a documentation generator that uses a simple folder structure and Markdown files to...
Docusaurus - Easy to maintain open source documentation websites
ReadMe - A collaborative developer hub for your API or code.