Removes comments

And introduction which is no longer relevant. Refs #2514 and it would
close it if it weren't by the fact that I have discovered a new
experimental feature, `smallnatives`, which begs documentation too.

doc/Language/experimental.pod6

@@ -12,13 +12,7 @@ example, like this:
 
     use experimental :macros;
 
-Following is a list of current experimental features and a short
-description of each feature's purpose or a link to more details about
-its use.  (Note: Features marked "[TBD]" are to be defined
-later.)
-
-=comment The following should be a table but formatting in tables is
-not yet rendered properly.
+These are the features that, for the time being, are experimental.
 
 =head2 X<B<pack>|pack>
 
@@ -28,7 +22,10 @@ L<Perl's pack|http://perldoc.perl.org/functions/pack.html>.
 The C<pack> order creates a
 C<Buf> by packing data structures in a certain way given by a I<packing string>
 with the options shown
-L<in the description of C<unpack>\/type/Blob#method_unpack>.
+L<in the description of C<unpack>\/type/Blob#method_unpack>. You turn it on by
+inserting this pragma at the beginning of your program:
+
+    use experimental :pack;
 
 For instance, we can pack numbers interpreting them as hexadecimal (C<H>) with
 the pattern repeating until there are no more elements (C<*>):