Hi dixonā,
There isn't documentation on using MEAN apps for Canvas, per se. LTI is an open standard, and therefore platform agnostic. Canvas doesn't know or care whether your app server is MEAN or XAMPP or .NET, or whether it's even a "server" at all, or a set of microservices. As long a server at the launch URL responds, LTI is happy.
There is a lot of good documentation from the community on building LTI integrations, though. I'd suggest starting with the LTI links Canvas Dev & Friends resource site or @garth collecton of LTI 1.x Useful Links.
For the node.js side, there are good examples in the documentation for the ims-lti NPM package.