Update json-last-error-msg.xml - json_validate() (#4721)

Co-authored-by: Niels Dossche <7771979+nielsdos@users.noreply.github.com>
Co-authored-by: Luffy <52o@qq52o.cn>

Author: 3 people

reference/json/functions/json-last-error-msg.xml

@@ -3,7 +3,7 @@
 <refentry xml:id="function.json-last-error-msg" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
  <refnamediv>
   <refname>json_last_error_msg</refname>
-  <refpurpose>Returns the error string of the last json_encode() or json_decode() call</refpurpose>
+  <refpurpose>Returns the error string of the last json_validate(), json_encode() or json_decode() call</refpurpose>
  </refnamediv>
 
  <refsect1 role="description">
@@ -13,7 +13,7 @@
    <void/>
   </methodsynopsis>
   <para>
-   Returns the error string of the last <function>json_encode</function> or <function>json_decode</function>
+   Returns the error string of the last <function>json_validate</function>, <function>json_encode</function> or <function>json_decode</function>
    call, which did not specify <constant>JSON_THROW_ON_ERROR</constant>.
   </para>