Explanation why SSP scenarios are not mentioned in file names

The following explanation why SSPs are not mentioned in file names has been added to section 2.5:
"As ISIMIP2b Group 3 only considers SSP2 and no other socio-economic storylines, the SSP scenario is not explicitly mentioned in the file names, although the changes in land-use patterns, etc. certainly not only depend on the RCP (due to the accounting for associated climate impacts of, e.g., crop yields), but also on the SSP."