new Enums references for Dossiers legislatifs on 2019-02-22 dump

There are new enum references that appeared in the last dump (22/02/2019).

I open this issue just to reference the new ones:

• CodeEspeceDocument : RECT -> I guess this means "Texte/loi rectificatif/ve"
• CodeDepotDocument : LRECT-> I guess this means "Loi rectificative"
• CodeClasseDocument : LETTRE -> this means "Lettre" which i don't know what could be the precise meaning.
• CodeTypeDocument : LETT -> Lettre ?

I've begun a fix to add those enums refs. I more enums refs shows up in this dump i'll update the issue, otherwise i'll push a Pull request later or more probably tomorrow morning.