doc: Mention PASSING support for jsonpath variables

Commit dfd79e2d added a TODO comment to update this paragraph
when support for PASSING was added.  Commit 6185c9737cf added
PASSING but missed resolving this TODO.  Fix by expanding the
paragraph with a reference to PASSING.

Author: Aditya Gollamudi <adigollamudi@gmail.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://postgr.es/m/20260117051406.sx6pss4ryirn2x4v@pgs

diff --git a/doc/src/sgml/json.sgml b/doc/src/sgml/json.sgml
index 206eadb8f7bafe84ef655aa3eb3b5c498274a7e7..8a2aad5935e9283cd834a1dfd31b5a322be097b0 100644 (file)
--- a/doc/src/sgml/json.sgml
+++ b/doc/src/sgml/json.sgml
@@ -882,9 +882,10 @@ UPDATE table_name SET jsonb_field[1]['a'] = '1';
       <entry><literal>$varname</literal></entry>
       <entry>
         A named variable. Its value can be set by the parameter
-        <parameter>vars</parameter> of several JSON processing functions;
-        see <xref linkend="functions-json-processing-table"/> for details.
-        <!-- TODO: describe PASSING clause once implemented !-->
+        <parameter>vars</parameter> of several JSON processing functions
+        (see <xref linkend="functions-json-processing-table"/>), or by
+        using the SQL/JSON <literal>PASSING</literal> clause as described
+        in <xref linkend="sqljson-query-functions"/>.
       </entry>
      </row>
      <row>