Link to TMI: Threat Modeling Improved

[jgadsden]

Describe what problem your feature request solves:
@ericfitz has created an interesting open-source threat modeling tool "TMI: Threat Modeling Improved" which we should reasonably support in the same way as we support pytm
It is a threat modeling tool that the Threat Dragon community may well want to consider

Describe the solution you'd like:
It would be good to link across to TMI, same as we do with pytm, probably in the docs and the README

Additional context:
TMI link: https://www.tmi.dev/
TMI repo: https://github.com/ericfitz/tmi-ux

[Devesh36]

@jgadsden can i try this ?