Document WhateverCode end point in Range

A WhateverCode end point to the Range operator creates a new WhateverCode
which returns Ranges.

This is covered by roast: https://github.com/perl6/roast/blob/master/S02-types/whatever.t#L34

doc/Type/Range.pod6

@@ -48,6 +48,18 @@ Use C<∞> or C<*> (Whatever) to indicate an end point to be open-ended.
 for 1..* { .say };       # start from 1, continue until stopped
 for 1..∞ { .say };       # the same
 
+Beware that a L<WhateverCode|/type/WhateverCode> end point, instead of a plain
+Whatever, will go through the range operator and create another WhateverCode
+which returns a Range:
+
+=for code
+# A Whatever produces the 1..Inf range
+say (1..*).WHAT;         # OUTPUT: «(Range)␤»
+say (1..*);              # OUTPUT: «1..Inf␤»
+# Upper end point is now a WhateverCode
+say (1..*+20).WHAT;      # OUTPUT: «(WhateverCode)␤»
+say (1..*+20).(22);      # OUTPUT: «1..42␤»
+
 Ranges implement L<Positional|/type/Positional> interface, so its elements can
 be accessed using an index. In a case when the index given is bigger than the
 Range object's size, L<Nil|/type/Nil> object will be returned. The access works