pattern regex anchor text to patternProperties

Copied the text about regexes not being anchored from "pattern"
to the analogous location in "patternProperties".

Author: handrews

jsonschema-core.xml

@@ -2446,7 +2446,8 @@
                             Validation succeeds if, for each instance name that matches any
                             regular expressions that appear as a property name in this keyword's value,
                             the child instance for that name successfully validates against each
-                            schema that corresponds to a matching regular expression.
+                            schema that corresponds to a matching regular expression.  Recall: regular
+                            expressions are not implicitly anchored.
                         </t>
                         <t>
                             The annotation result of this keyword is the set of instance