Minor fixes

Author: JJ

doc/Type/Supply.pod6

@@ -429,10 +429,10 @@ method throttle(Supply:D:
   --> Supply:D)
 
 Produces a C<Supply> from a given Supply, but makes sure the number of
-messages passed through, is limited.
+messages passed through is limited.
 
 It has two modes of operation: per time-unit or by maximum number of
-execution of a block of code: this is determined by the second positional
+executions of a block of code: this is determined by the second positional
 parameter.
 
 The first positional parameter specifies the limit that should be applied.