More misc. typos
found via `codespell-q 3`
please review
diff --git a/pngrtran.c b/pngrtran.c
index 5c4128d..40c2ce5 100644
--- a/pngrtran.c
+++ b/pngrtran.c
@@ -2979,7 +2979,7 @@
* values this results in an implicit assumption that the original PNG RGB
* values were linear.
*
- * Other integer coefficents can be used via png_set_rgb_to_gray(). Because
+ * Other integer coefficients can be used via png_set_rgb_to_gray(). Because
* the API takes just red and green coefficients the blue coefficient is
* calculated to make the sum 32768. This will result in different rounding
* to that used above.