[Documentation] Update documentation according to QWAT user group needs

[kandre]

• Translate sections, titles, introduction that are not in french (needs transifex)

• Modifications of table of contents tree :

  • Translation to french (needs transifex)
  • Delete or remove Translation (10) section
  • Remove Glossary (9), section as long as there is not more stuff in it
  • Move Features (1) section into Admin section

• Revision of the "Directive de saisie des conduites" according to the last updates of SIRE, summarise geoemetry editing constraints and possibly add references to the SIRE directive with links and illustrations.

• Add a link to QGIS documentation at the beginning of the « QWAT User guide »

• Add a section about the schematic concept in QWAT along with a procedure to follow when "broken".

• Generally speaking, add illustrations with geographical data to features descriptions and documentation.

• Add links to QWAT related plugins such as Link It, etc.

Some points are on hold waiting to migrate to transifex.

[nliaudat]

Add link to qwat extension https://github.com/nliaudat/ch_fr_aquafri
Add link to qwat import sample https://github.com/nliaudat/qwat-import-sample

or better merge all into official repo.
Regards

[ponceta]

@nliaudat the git model for QWAT extensions comes soon thanks to @lbartoletti