Clarify EUMETNET, RODEO and E-SOH relationship

[mortenwh]

E-SOH is a module of an EUMETNET Application Area, but called as WP3 from the RODEO project perspective and therefore being above the context of EUMETNET. This should be clarified in the introduction so that the text followed is in the right context. I understand that this text might have previously used in internal EUMETNET documentation