Fix the grant numbers for the support of PyGMT (#3347)

Author: yvonnefroehlich

doc/overview.md

@@ -22,7 +22,7 @@ The project was started in 2017 by [Leonardo Uieda](http://www.leouieda.com) and
 [Paul Wessel](http://www.soest.hawaii.edu/wessel) (the co-creator and main developer of
 GMT) at the University of Hawaiʻi at Mānoa. The development of PyGMT has been supported
 by NSF grants [OCE-1558403](https://www.nsf.gov/awardsearch/showAward?AWD_ID=1558403)
-and [EAR-1948603](https://www.nsf.gov/awardsearch/showAward?AWD_ID=1948602).
+and [EAR-1948602](https://www.nsf.gov/awardsearch/showAward?AWD_ID=1948602).
 
 We welcome any feedback and ideas! Let us know by submitting
 [issues on GitHub](https://github.com/GenericMappingTools/pygmt/issues) or by posting on