Today we are entering the public beta phase of MathJax v2.2. This release includes a number of new features and increased stability with over 40 bug fixes. It is available at cdn.mathjax.org/mathjax/2.2-beta/MathJax.js which you can load in place of the version you are currently using. Alternatively, you can get a ZIP archive to use locally or you can check out the v2.2-beta branch of MathJax by using the commands
For documentation on ContenMathML, please see the MathML specification.