change table to delimited block form

remove :nested config key

Author: tbrowder

doc/Language/pod.pod6

@@ -45,14 +45,15 @@ configuration information for the block. This information is used in
 different ways by different types of blocks, but is always specified using
 Perl6-ish option pairs. That is, any of:
 
-=for table :nested
+=begin table
  Value is...       Specify with...       Or with...       Or with...
  ===============   ===================   ==============   ======================
  Boolean (true)    :key                  :key(1)          key => 1
  Boolean (false)   :!key                 :key(0)          key => 0
  String            :key<str>             :key('str')      key => 'str'
  List              :key<1 2 3>           :key[1,2,3]      key => [1,2,3]
  Hash              :key{a=>1, b=>2}                       key => {a=>1, b=>2}
+=end table
 
 All option keys and values must, of course, be constants since Pod is a
 specification language, not a programming language. Specifically, option