build: recommend boost >= 1.65.1
With this commit, Ubuntu 16.04 is no longer officially supported
and may require manual installation of a newer version of Boost.
Refs: #5087
Change-Id: I17197f72ee8f7cd4d0954658fe57c324076f1311
diff --git a/docs/tutorials/utils-ndn-regex.rst b/docs/tutorials/utils-ndn-regex.rst
index af107c0..52026ae 100644
--- a/docs/tutorials/utils-ndn-regex.rst
+++ b/docs/tutorials/utils-ndn-regex.rst
@@ -5,8 +5,8 @@
performed at two levels: the name level and the name component level.
A name component matcher, enclosed in ``<`` and ``>``, specifies the pattern of a name component. The
-component pattern is expressed with the `Perl Regular Expression Syntax
-<https://www.boost.org/doc/libs/1_58_0/libs/regex/doc/html/boost_regex/syntax/perl_syntax.html>`__.
+component pattern is expressed using the `Modified ECMAScript Regular Expression Syntax
+<https://en.cppreference.com/w/cpp/regex/ecmascript>`_.
For example, ``<ab*c>`` matches the 1st, 3rd, and 4th components of ``/ac/dc/abc/abbc``, but does
not match the 2nd component. A special case is that ``<>`` denotes a wildcard matcher that can match
**ANY** name component.