Tobi: tutorial

What

This merge request introduces Tobi's documentation. For now it only contains a tutorial, but the full version will be more comprehensive.

Why

So that people can learn how to use Tobi.

How

I am following guidelines from https://diataxis.fr/ to write Tobi's documentation.

The documentation itself is written in markdown. A Makefile allows to convert it to HTML. To do that, markdown needs to be installed (apt-get install markdown). But the markdown version can already be read easily, e.g. in GitLab's interface.

Manually testing the MR

sudo apt-get install markdown
cd tobi/doc
make
open html/index.html

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR