Remove redundant text describing the cleanup routine.

Upstreamed:
    http://code.google.com/p/kyua/issues/detail?id=43

Submitted by:	Garrett Cooper <yanegomi@gmail.com>

contrib/atf/doc/atf-test-case.4

@@ -61,7 +61,7 @@ failures.
 This body is only executed if the abstract conditions specified by the
 header are met.
 The
-.Em cleanup routine
+.Em cleanup
 routine is a piece of code always executed after the body, regardless of
 the exit status of the test case.
 It can be used to undo side-effects of the test case.