A typo fixed.

Author: proway2

README.md

@@ -48,7 +48,7 @@ There are almost 900 unittests and results are compared against those generated
 
 Since FORTRAN rounds almost all values, except `D` and `I`, actual results are of much higher accuracy.
 
-## Hot to use
+## How to use
 
 - Add `"github.com/proway2/go-igrf/igrf"` to your import clause.
 
@@ -72,4 +72,4 @@ func main() {
 
 - [Alken, P., Thébault, E., Beggan, C.D. et al. International Geomagnetic Reference Field: the thirteenth generation. Earth Planets Space 73, 49 (2021).](https://rdcu.be/cKqZv) https://doi.org/10.1186/s40623-020-01288-x
 
-- Implementation is based on [geomag70.c](https://www.ngdc.noaa.gov/IAGA/vmod/geomag70_linux.tar.gz). [License information](https://www.ngdc.noaa.gov/IAGA/vmod/geomag70_license.html).
+- Implementation is based on [geomag70.c](https://www.ngdc.noaa.gov/IAGA/vmod/geomag70_linux.tar.gz). [License information](https://www.ngdc.noaa.gov/IAGA/vmod/geomag70_license.html).