Fix description for $varname jsonpath variable

The description is ended part way and PASSING clause is not implemented yet.
But the variables might be passed as parameters to several jsonpath functions.
So, complete the description based on the current implementation, leaving
description of PASSING clause in TODO.

Discussion: https://postgr.es/m/CAKPRHz%2BxOuQSSvkuB1mCQjedd%2BB2B1Vnkrq0E-pLmoXyTO%2Bz9Q%40mail.gmail.com
Author: Kyotaro Horiguchi, Alexander Korotkov

diff --git a/doc/src/sgml/json.sgml b/doc/src/sgml/json.sgml
index b8246badda9b402bab06482a0e83144a63e5d2fe..daebb4f3410204f006ab1f067fa6892105de8613 100644 (file)
--- a/doc/src/sgml/json.sgml
+++ b/doc/src/sgml/json.sgml
@@ -733,10 +733,12 @@ SELECT jdoc->'guid', jdoc->'name' FROM api WHERE jdoc @> '{"tags": ["qu
      
      
       $varname
-      A named variable. Its value must be set in the
-      PASSING clause of an SQL/JSON query function.
- 
-      for details.
+      
+        A named variable. Its value can be set by the parameter
+        vars of several JSON processing functions.
+        See  and
+        its notes for details.
+