Remove confusing parentheses in README

Author: laughinghan

README.md

@@ -303,7 +303,7 @@ out into the share/ottypes library and its finally landed here.
 The type uses the list-of-op-components model, where each operation makes a
 series of individual changes to a document. Joseph now thinks this is a
 terrible idea because it doesn't scale well to large operations - it has
-(N<sup>2</sup> instead of 2N complexity).
+N<sup>2</sup> instead of 2N complexity.
 
 Jeremy and Joseph have talked about rewriting this library to instead make each
 operation be a sparse traversal of the document. But it was obnoxiously