Wording polish

Author: fdwr

index.bs

@@ -2833,7 +2833,7 @@ partial interface MLGraphBuilder {
     <summary>
     The behavior of this operation can be generically emulated from the usage of
     other operations as follows. However, user agents typically have a more
-    efficient implementation for it, therefore its usage is encouraged from the
+    efficient implementation for it. Therefore its usage is encouraged from the
     performance standpoint.
     </summary>
     <pre highlight="js">