build: require gcc >= 5.3, boost >= 1.58, openssl >= 1.0.2
This effectively drops support for all versions of Ubuntu older than 16.04
Change-Id: Ie3ab7df9147e97f6467658a6399a4f9379f089c1
Refs: #4462
diff --git a/docs/tutorials/utils-ndn-regex.rst b/docs/tutorials/utils-ndn-regex.rst
index 6492a96..af107c0 100644
--- a/docs/tutorials/utils-ndn-regex.rst
+++ b/docs/tutorials/utils-ndn-regex.rst
@@ -6,7 +6,7 @@
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
-<http://www.boost.org/doc/libs/1_55_0/libs/regex/doc/html/boost_regex/syntax/perl_syntax.html>`__.
+<https://www.boost.org/doc/libs/1_58_0/libs/regex/doc/html/boost_regex/syntax/perl_syntax.html>`__.
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.