Give ECMA 262 reference section for RegExp dialect.

Author: handrews

jsonschema-core.xml

@@ -552,8 +552,8 @@
                 <t>
                     Keywords MAY use regular expressions to express constraints, or constrain
                     the instance value to be a regular expression.
-                     These regular expressions SHOULD be valid according to the
-                    <xref target="ecma262">ECMA 262</xref> regular expression dialect.
+                    These regular expressions SHOULD be valid according to the regular expression
+                    dialect described in <xref target="ecma262">ECMA 262, section 15.10.1</xref>.
                 </t>
                 <t>
                     Furthermore, given the high disparity in regular expression constructs support,