Merge branch 'siconc_sivol_scenarios' into 'master'

Add seaice data for all models and two scenarios (closes #9)

See merge request rcdl/synda-selections!12

CMIP6_all-models_ScenarioMIP_ssp126_all-members.txt

+project=CMIP6
+activity_id=ScenarioMIP
+experiment_id=ssp126
+latest=true
+
+# SImon
+variable[SImon]=siconc
+variable[SImon]=sivol

CMIP6_all-models_ScenarioMIP_ssp585_all-members.txt

+project=CMIP6
+activity_id=ScenarioMIP
+experiment_id=ssp585
+latest=true
+
+# SImon
+variable[SImon]=siconc
+variable[SImon]=sivol