Fix typo in doc
diff --git a/include/mbedtls/md.h b/include/mbedtls/md.h
index 2a6cc0c..19df9e8 100644
--- a/include/mbedtls/md.h
+++ b/include/mbedtls/md.h
@@ -154,7 +154,7 @@
  *
  * \param ctx       Context to set up.
  * \param md_info   Message digest to use.
- * \param hmac      0 to save some meory is HMAC will not be use,
+ * \param hmac      0 to save some memory if HMAC will not be used,
  *                  non-zero is HMAC is going to be used with this context.
  *
  * \returns         \c 0 on success,