Add "Set up environment" module

[jaguarfi]

Description

A new module is created to guide the reader through the installation of the required software and the setting up of the development environment.

Create this new module required to move some of the existing chapters to different parts of the manual, including the new module.

Testing

The content was tested manually. The test was merely to check that the content of the manual was rendered as intended.

Is it Done?

Clean up your git commit history before submitting the pull request!

• [X] I (developer) have tested the changes manually
• [ ] Reviewer has finished the code review
• [ ] After the review, the developer has made changes accordingly
• [ ] Customer/Teacher has accepted the implementation of the feature

[jaguarfi]

I had to force-push. I rebased the branch into master, but I have applied all the required changes.

[jaguarfi]

Yes, the extension will keep the publisher, otherwise, the extension will stop working for those who have already downloaded it. But, the new publisher "apluslms" should be able to completely manage the extension. Any case, I sent another email asking about changing the URL, but I have not gotten a response.