Cosmetic punctuation fix in comment

BUG=aomedia:2959

Change-Id: Ifec9407ee419d7c3b62dda8ed2cedec1853bd137
diff --git a/aom/aom_encoder.h b/aom/aom_encoder.h
index 7d86c8b..1d9c0b4 100644
--- a/aom/aom_encoder.h
+++ b/aom/aom_encoder.h
@@ -949,9 +949,8 @@
  * \param[in]    iface     Pointer to the algorithm interface to use.
  * \param[out]   cfg       Configuration buffer to populate.
  * \param[in]    usage     Algorithm specific usage value. For AV1, must be
- *                         set to AOM_USAGE_GOOD_QUALITY (0) or
- *                         AOM_USAGE_REALTIME (1),
- *                         AOM_USAGE_ALL_INTRA (2).
+ *                         set to AOM_USAGE_GOOD_QUALITY (0),
+ *                         AOM_USAGE_REALTIME (1), or AOM_USAGE_ALL_INTRA (2).
  *
  * \retval #AOM_CODEC_OK
  *     The configuration was populated.