Add mlx-teacache (MLX / Apple Silicon) to Community Contributions

[IonDen]

Hi, and thanks for TeaCache; it's the basis for an MLX / Apple Silicon port I maintain.

mlx-teacache brings TeaCache to mflux (FLUX.1 and FLUX.2) on Apple Silicon, in pure MLX. I've added one line under Engine in Community Contributions, matching the existing format.

This is entirely your call: please feel free to reword it, move it to a better subsection, or close this if you'd rather not list third-party ports. README-only change, no code.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}