Updated suggestion docs/api/covidcast_changelog.md

Co-authored-by: Katie Mazaitis <[email protected]>

Author: Akvannortwick

docs/api/covidcast_changelog.md

@@ -26,7 +26,7 @@ changes, data corrections, and other information relevant to API users.
 ## Sources and Signals
 ### `doctor-visits`
 #### 9 November 2020
-We went from a custom geo mapping file (for aggregating from zip->(county, msa, hrr, state)) to a central geo file based on rigorously sourced US census data.
+We went from a custom geo mapping file (for aggregating from county->(msa, hrr, state)) to a central geo file based on rigorously sourced US census data.
 
 ### `fb-survey`