fix boost version mentioned, per #47

Author: pryrt

content/docs/searching.md

@@ -275,7 +275,7 @@ In extended mode, these escape sequences (a backslash followed by a single chara
 
 ## Regular Expressions
 
-Notepad++ regular expressions use the Boost regular expression library v1.55, which is based on PCRE (Perl Compatible Regular Expression) syntax, only departing from it in very minor ways. Complete documentation on the precise implementation is to be found on the Boost pages for [search syntax](https://www.boost.org/doc/libs/1_70_0/libs/regex/doc/html/boost_regex/syntax/perl_syntax.html) and [replacement syntax](https://www.boost.org/doc/libs/1_70_0/libs/regex/doc/html/boost_regex/format/boost_format_syntax.html)
+Notepad++ regular expressions use the Boost regular expression library v1.70, which is based on PCRE (Perl Compatible Regular Expression) syntax, only departing from it in very minor ways. Complete documentation on the precise implementation is to be found on the Boost pages for [search syntax](https://www.boost.org/doc/libs/1_70_0/libs/regex/doc/html/boost_regex/syntax/perl_syntax.html) and [replacement syntax](https://www.boost.org/doc/libs/1_70_0/libs/regex/doc/html/boost_regex/format/boost_format_syntax.html)
 
 The Notepad++ Community has a [FAQ on other resources for regular expressions](https://notepad-plus-plus.org/community/topic/15765/faq-desk-where-to-find-regex-documentation).