Fix copy paste error, thanks @ns-rse

Co-authored-by: Neil Shephard <[email protected]>

README.md

@@ -58,7 +58,7 @@ frames, pixel_to_nanometre_scaling_factor, metadata = load_asd(file_path="./my_a
 
 ### .ibw
 
-You can open `.spm` files using the `load_spm` function. Just pass in the path to the file
+You can open `.ibw` files using the `load_ibw` function. Just pass in the path to the file
 and the channel name that you want to use. (If in doubt, use `HeightTracee` (yes, with the
 exta 'e'), `ZSensorTrace`, or `ZSensor`).