feat: add completion command

[Zamoca42]

Description

I've implemented the auto-completion feature suggested in roadmap issue #342.

A new completion.js file was created to generate and install auto-completion scripts for both bash and zsh shells. I've also added a completion command to bin/tldr.

Images showing the feature in action are attached.

Details

• Added completion.js to handle completion script generation and installation
• Updated bin/tldr to include a new completion command
• Supports both bash and zsh shells
• Automatically adds completion scripts to the user's shell configuration file

I hope this feature makes using tldr even more convenient.

zsh

bash

Checklist

Please review this checklist before submitting a pull request.

• Code compiles correctly
• Created tests, if possible
• All tests passing (npm run test:all)
• Extended the README / documentation, if necessary

Related

Closes #342

[renie]

Just a small consideration on README.
The code itself LGTM. I will run a couple of tests on this branch just to be sure, and comment here as soon as it is all checked.
Thanks for the contribution, @Zamoca42 ! 🥇

[renie]

It works like a charm, @Zamoca42 ! Thanks a lot! 🔥
Just have a look at the change requested, please.

[renie]

All good now!

[kbdharun]

LGTM, Thanks for your contribution. If possible, can you revert the oh my zsh plugin section beside the new zsh docs (the zplug one isn't required) since it allows using the commands with shortcuts?

[Zamoca42]

@kbdharun I have reverted the oh-my-zsh plugin section in README!
Let me know if there are any other changes needed. 😄