typo

docs/state.rst

@@ -22,7 +22,7 @@ The state property can be used the same way as a regular property.
         }
     }
 
-Propogate the State
+Propagate the State
 ======================
 A contract can keep state across chained transactions by storing it in the locking script.
 In the following example, a contract goes from ``state0`` to ``state1``, and then to ``state2``.