Transition to EML 2.2.0

[earnaud]

As EML 2.2.0 was released on Friday 13t of September, MetaShARK shall be upgraded within this new version.
The main change will concern the doc. Its resource will be renewed, and the elder ones will be dropped in old directory of /shinyapp.
To get up-to-date, some changes are to come:

• [x] dev and master will be merged to save dev's advances, even if a "Under construction panel" will appear in the Fill section of MetaShARK.
• [x] new dev will be dedicated to EML transition to 2.2.0 (mainly in Documentation module). This will result in a second merge of dev.
  • [x] substep 1: re-process EML guidelines
  • [x] substep 2 : check for the modules' documentation completeness
• [x] a new-new dev will continue EML AL integration when MetaShARK will be updated.

[earnaud]

Objectives have been reached with the only exception:

• high-level XSD nodes (aka modules' R lists' roots) are not documented since the NCEAS team decided to remove their documentation from within the XSD themselves. No alternative documentation has been provided, so they are left blank.

It is now possible to:

• access origin documentation
• access full references of the app