Add word to comment (minor)

src/write.c

diff --git a/src/write.c b/src/write.c
index 2068fff..ce1cf9a 100644
--- a/src/write.c
+++ b/src/write.c
@@ -570,7 +570,7 @@
         uint32_t contentSize = (uint32_t)item->metadataPayload.size;
         if (item->encodeOutput->samples.count > 0) {
             // This is choosing sample 0's size as there are two cases here:
-            // * This is a single image, in which this is correct
+            // * This is a single image, in which case this is correct
             // * This is an image sequence, but this file should still be a valid single-image avif,
             //   so there must still be a primary item pointing at a sync sample. Since the first
             //   frame of the image sequence is guaranteed to be a sync sample, it is chosen here.