Temporarily remove mentions of Scheduler.cue edge case version reqs

It may be in 2019.05, but may have to wait until 2019.06, but either
way, 2019.04 isn't a version.

Author: Kaiepi

doc/Type/Scheduler.pod6

@@ -55,7 +55,7 @@ If C<$at> or C<$in> are C<Inf>, C<&code> will never be run; if C<$every> is
 C<Inf>, C<&code> will only be run once. If any of the three are C<-Inf>,
 C<&code> will be run immediately. If any of the three are C<NaN>, an
 L<X::Scheduler::CueInNaNSeconds|/type/X/Scheduler/CueInNanSeconds> exception
-will be thrown. This only applies to versions 2019.04 and later.
+will be thrown.
 
 One should call the C<cancel> method on the returned C<Cancellation> object
 to cancel the (possibly repeated) cueing of the code.

doc/Type/X/Scheduler/CueInNaNSeconds.pod6

@@ -6,9 +6,9 @@
 
     class X::Scheduler::CueInNaNSeconds is Exception { }
 
-In versions 2019.04 and later, when calling C<ThreadPoolScheduler.cue> or
-C<CurrentThreadScheduler.cue> with C<:at>, C<:in>, or C<:every> as C<NaN>, this
-exception gets thrown. For example, the following code:
+When calling C<ThreadPoolScheduler.cue> or C<CurrentThreadScheduler.cue> with
+C<:at>, C<:in>, or C<:every> as C<NaN>, this exception gets thrown. For
+example, the following code:
 
 =for code :skip-test
 my Cancellation $c = $*SCHEDULER.cue({