Add :123abc form to Pair description

doc/Language/terms.pod6

@@ -71,17 +71,19 @@ These forms produce regex literals. See L<Quoting Constructs|/language/quoting>.
     :identifier($value)
     :identifier['val1', 'val2']
     :identifier{key1 => 'val1', key2 => 'value2'}
+    :valueidentifier
     :$item
     :@array
     :%hash
     :&callable
 
 L<Pair> objects can be created either with C<< infix:«=>» >> (which
 auto-quotes the left-hand side if it is an identifier), or with the various
-colon-pair forms. Those always start with a colon and then are followed
+colon-pair forms. Those almost always start with a colon and then are followed
 either by an identifier or the name of an already existing variable (whose
 name without the sigil is used as the key and value of the variable is used
-as the value of the pair).
+as the value of the pair). There is a special form where an integer value
+is immediately after the colon and the key is immediately after the value.
 
 In the identifier form of a colon-pair, the optional value can be any
 circumfix.  If it is left blank, the value is C<Bool::True>. The value of