manual.yml - Perl NG (#2614)

docs/content/manual/manual.yml

@@ -2304,9 +2304,12 @@ sections:
 
       jq uses the
       [Oniguruma regular expression library](https://github.com/kkos/oniguruma/blob/master/doc/RE),
-      as do PHP, Ruby, TextMate, Sublime Text, etc, so the
+      as do PHP, TextMate, Sublime Text, etc, so the
       description here will focus on jq specifics.
 
+      Oniguruma supports several flavors of regular expression, so it is important to know
+      that jq uses the ["Perl NG" (Perl with named groups)](https://github.com/kkos/oniguruma/blob/master/doc/SYNTAX.md) flavor.
+
       The jq regex filters are defined so that they can be used using
       one of these patterns:
 
@@ -2321,6 +2324,10 @@ sections:
       * REGEX, after string interpolation, should be a valid regular expression;
       * FILTER is one of `test`, `match`, or `capture`, as described below.
 
+      Since REGEX must evaluate to a JSON string, some characters that are needed
+      to form a regular expression must be escaped. For example, the regular expression
+      `\s` signifying a whitespace character would be written as `"\\s"`.
+
       FLAGS is a string consisting of one of more of the supported flags:
 
       * `g` - Global search (find all matches, not just the first)