Explain semantics of <( )> inside []* and ()*

fixes #60

S05-regex.pod

@@ -16,8 +16,8 @@ Synopsis 5: Regexes and Rules
 
     Created: 24 Jun 2002
 
-    Last Modified: 21 Aug 2013
-    Version: 165
+    Last Modified: 18 Sep 2013
+    Version: 166
 
 This document summarizes Apocalypse 5, which is about the new regex
 syntax.  We now try to call them I<regex> rather than "regular
@@ -1973,7 +1973,18 @@ based on those positions.  For instance, after the match above, C<$()> contains
 only the digits matched, and C<$/.to> is pointing to after the digits. Other
 captures (named or numbered) are unaffected and may be accessed through C<$/>.
 
-These tokens are considered declarative, but may force backtracking behavior.
+When used directly within quantifiers (that is, within quantified
+square brackets), there is only one C<Match> object to set
+C<.from>/C<.to> on, so the C<< <( >> token always sets C<.from> to
+the leftmost matching position, while C<< )> >> always sets C<.to>
+to the rightmost position.  However, the situation is different for
+capturing parentheses.  When used within parentheses (whether or
+not the parens are quantified), the C<Match> being generated by each
+dynamic capture serves as the target, so each such capturing group
+sets its own C<.from>/C<.to>.  Hence, if the group is quantified,
+each capture sets its own boundaries independently.
+
+These tokens are considered declarative.
 
 =item *