Fixed minor typo (#3165)

include/avif/avif_cxx.h

diff --git a/include/avif/avif_cxx.h b/include/avif/avif_cxx.h
index 7a7723c..6d132ca 100644
--- a/include/avif/avif_cxx.h
+++ b/include/avif/avif_cxx.h
@@ -30,7 +30,7 @@
 using GainMapPtr = std::unique_ptr<avifGainMap, UniquePtrDeleter>;
 using ImagePtr = std::unique_ptr<avifImage, UniquePtrDeleter>;
 
-// Automatically cleans the ressources of the avifRGBImage.
+// Automatically cleans the resources of the avifRGBImage.
 // To use when RGBImage actually owns the pixels. RGBImage can also be used as a view, in which case it does not own the pixels.
 class RGBImageCleanup
 {