Create guide/examples for doing common things in dune

[sphinxc0re]

There are already a lot of features that are very well explained through the README. I feel like the project would profit from a step-by-step guide through some of the most common scenarios:

• completion
• aliases (e.g. dc for docker compose)
• examples for integrating common developer tools like nvm, volta, rbenv, frum, zoxide, etc...

I would also like to offer my input on these topics but feel unable to write it myself as I don't really know that much about the shell.

EDIT: Maybe there could be a section detailing the differences between a posix-like shell and dune or even a table to compare implementations of different features in each shell.