Regex: add \b to search, as regex depreciated → <|w>

Will allow users of other languages to look it up by searching
for this.

doc/Language/regexes.pod6

@@ -555,7 +555,7 @@ character to the right.
 C<<< >> >>> matches a right word boundary: it matches positions where there
 is a word character at the left and a non-word character at the right (or
 the end of the string). If you want to match any word boundary you can use
-C«<|w>»
+C«<|w>». This is similar to other languages X«C<\b>|regex depreciated,\b».
 
     my $str = 'The quick brown fox';
     say so $str ~~ /br/;              # True