Removed reference to the clocked variant from the readme.

README.md

@@ -11,13 +11,12 @@ and simple denotational semantics.
 Stateful signals can be safely generated at any time through a monadic
 interface, while stateless combinators can be used in a purely
 applicative style.  Elerea signals can be defined recursively, and
-external input is trivial to attach.  The library comes in three major
+external input is trivial to attach.  The library comes in two major
 variants:
 
 * **Simple**: signals are plain discrete streams isomorphic to
     functions over natural numbers;
 * **Param**: adds a globally accessible input signal for convenience;
-* **Clocked**: adds the ability to freeze whole subnetworks at will.
 
 This is a minimal library that defines only some basic primitives, and
 you are advised to install