Add mise installation instructions to documentation #844

For Linux users, add instructions in the README to use mise to install Overmind CLI, as a streamlined alternative to the current Ubuntu / Debian manual install instructions.

• Provide examples of installing mise for Ubuntu/Debian (perhaps other Linux distros?).
• Show how to use mise to install the Overmind CLI.
• Reference the official mise quickstart (https://github.com/jdx/mise?tab=readme-ov-file#quickstart).

References:

• mise docs: https://github.com/jdx/mise?tab=readme-ov-file#quickstart
• Context: User validated mise use overmind works on Ubuntu 24.04
• mise cookbook for terraform

Example outline to include in docs:

Installing mise

See the mise quickstart or:

Ubuntu/Debian

curl https://mise.run | bash

Installing Overmind CLI using mise

mise use overmind