WIP: Append more languages on implementing of the extra backend

[Aisuko]

Add more detail for the the extra backend, like below:

• How to create a seperate Python environment for the extra backend was implemented by Python
• Add the detail for Rust backend
• Add the detail for C++ backend

And this PR will also going to add

• the URL of new backend to the main Dockerfile
• the command of prepare the extra backend env

This PR is needed to update after these backend was implemented and it's PR to get to merged. So, it is a draft status.

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[lunamidori5]

Looks good from my POV will wait to merge until ready <3

[Aisuko]

Thank you.