Fix typo

Author: slevis-lmwg

datm/cime_config/stream_definition_datm.xml

@@ -152,7 +152,7 @@
   ========================
   optional stream co2tseries (turned on and stream specified by xml variable DATM_CO2_TSERIES)
   - DATM_CO2_TSERIES is set by the 4 character time prefix in config_component.xml
-  - The historical series are labeled as either CMIP6 or CMIP6 era
+  - The historical series are labeled as either CMIP6 or CMIP7 era
   - The SSP future scenarios are all CMIP6 era data
   ========================
   co2tseries.cmip6_20tr