Fix a missing quote in the "readOnly and writeOnly" section

Author: hkosova

jsonschema-validation.xml

@@ -1201,7 +1201,7 @@
                     expected to be ignored or rejected by that owning authority.
                 </t>
                 <t>
-                    An instance document that is marked as "readOnly for the entire document
+                    An instance document that is marked as "readOnly" for the entire document
                     MAY be ignored if sent to the owning authority, or MAY result in an
                     error, at the authority's discretion.
                 </t>