Update settings and documentation

Author: tsmbland

src/muse/data/example/default/settings.toml

@@ -67,6 +67,11 @@ existing_capacity = '{path}/technodata/power/ExistingCapacity.csv'
 lpsolver = "scipy"
 demand_share = "standard_demand"
 
+[[sectors.power.outputs]]
+quantity = "supply"
+sink = "aggregate"
+filename = "{cwd}/{default_output_dir}/{Sector}_{Quantity}.csv"
+
 [sectors.gas]
 type = 'default'
 priority = 3