Fix up desc of :2foo format in .later

Don't make it sound like this is some "special syntax"
for .later calls, as it's just another colonpair format.

Author: zoffixznet

doc/Type/DateTime.pod6

@@ -273,8 +273,8 @@ C<hours>, C<day>, C<days>, C<week>, C<weeks>, C<month>, C<months>, C<year>,
 C<years>.   Please note that the plural forms can only be used with
 the C<later> method.
 
-Please note that the special ":2nd" named parameter syntax can be a compact
-and self-documenting way of specifying the delta
+The C<:2nd> form of colonpairs can be used as a compact and self-documenting
+way of specifying the delta:
 
     say DateTime.new('2015-12-24T12:23:00Z').later(:2years); # OUTPUT: «2017-12-24T12:23:00Z␤»