Clean up comment formatting in md.h
diff --git a/include/mbedtls/md.h b/include/mbedtls/md.h
index b902355..9b996a9 100644
--- a/include/mbedtls/md.h
+++ b/include/mbedtls/md.h
@@ -304,8 +304,8 @@
/**
* \brief Output HMAC.
* Called after mbedtls_md_hmac_update().
- * Usually followed my mbedtls_md_hmac_reset(), mbedtls_md_hmac_starts(),
- * or mbedtls_md_free().
+ * Usually followed by mbedtls_md_hmac_reset(),
+ * mbedtls_md_hmac_starts(), or mbedtls_md_free().
*
* \param ctx HMAC context
* \param output Generic HMAC checksum result
@@ -317,7 +317,8 @@
/**
* \brief Prepare to authenticate a new message with the same key.
- * Called after mbedtls_md_hmac_finish() and before mbedtls_md_hmac_update().
+ * Called after mbedtls_md_hmac_finish() and before
+ * mbedtls_md_hmac_update().
*
* \param ctx HMAC context to be reset
*