Missing storage_capacity for BE-hydro-rsv

[eosram]

I guess, you've seen that already, because it's easy to see. Although there is reservoir capacity there is no storage capacity set for Belgium in all datapackages. Of course this problem exists in the input data already.

I thought Table 2 in this publication might be good data source. But it's again not that simple with hydro : ). I would guess, it does not affect the overall results much, so it's most likely low priority. Still I think it's useful to have this issue.