Integrate reworked documentation (developer...) into new documentation site

[Mathieu Rossignol]

This issue #466 has introduced a refactoring of the documentation. This work has been merged into the develop branch with the PR #471. But between the time where this PR has been merged and now, some documentation sources (developer, components...others ?) have disappeared (when and where?).

These sources are used for generating the documentation site https://logisland.readthedocs.io. One can see that it now heavily differs from the doc a the time of the PR: https://logisland.readthedocs.io/en/feature-logisland-466/developer/index.html

However, we now have a new documentation website located at https://logisland.github.io and whose sources are in this repo: https://github.com/logisland/docs.

The present issue is logged to keep track of the fact that we have to integrate what had been done in the rework of #466 in the new logisland documentation website. Sepcially it would be a pity to loose the developer guide...

[Mathieu Rossignol]

Found when those docs have been deleted : in the merge of the release/v1.3.0 branch into the master (4478742) :

[Séguin-Henry Grégoire]

In the history of the directory logisland-documentation https://github.com/Hurence/logisland/commits/master/logisland-documentation, We can see that the documentation is the commit 4c6c44d but not in the next.