Converted all links to www.boost.org to https.

Closes https://github.com/boostorg/integer/pull/25.

doc/Jamfile.v2

@@ -2,7 +2,7 @@
 
 # Copyright John Maddock 2005. Use, modification, and distribution are
 # subject to the Boost Software License, Version 1.0. (See accompanying
-# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+# file LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt)
 
 using quickbook ;
 
@@ -47,7 +47,7 @@ boostbook standalone
         # better use SVG's instead:
         <format>pdf:<xsl:param>admon.graphics.extension=".svg"
         <format>pdf:<xsl:param>admon.graphics.path=$(boost-images)/
-        <format>pdf:<xsl:param>boost.url.prefix=http://www.boost.org/doc/libs/release/libs/regex/doc/html
+        <format>pdf:<xsl:param>boost.url.prefix=https://www.boost.org/doc/libs/release/libs/regex/doc/html
     ;
 
 install pdfinstall : standalone/<format>pdf : <location>. <install-type>PDF ;