commit 93f11aead5da9f62310a6a82214ae43a78112a5a
Author: Alexander Korotkov <akorotkov@postgresql.org>
Date:   Fri May 17 05:16:31 2019 +0300

    Document jsonpath .** accessor with nesting level filter
    
    It appears that some variants of .** jsonpath accessor are undocumented.  In
    particular undocumented variants are:
    
     .**{level}
     .**{lower_level to upper_level}
     .**{lower_level to last}
    
    This commit adds missing documentation for them.

diff --git a/doc/src/sgml/json.sgml b/doc/src/sgml/json.sgml
index 8c5df6f0bb0..548cd9da7b6 100644
--- a/doc/src/sgml/json.sgml
+++ b/doc/src/sgml/json.sgml
@@ -807,6 +807,30 @@ SELECT jdoc-&gt;'guid', jdoc-&gt;'name' FROM api WHERE jdoc @&gt; '{"tags": ["qu
        </para>
       </entry>
      </row>
+     <row>
+      <entry>
+       <para>
+        <literal>.**{<replaceable>level</replaceable>}</literal>
+       </para>
+       <para>
+        <literal>.**{<replaceable>lower_level</replaceable> to
+        <replaceable>upper_level</replaceable>}</literal>
+       </para>
+       <para>
+        <literal>.**{<replaceable>lower_level</replaceable> to
+        last}</literal>
+       </para>
+      </entry>
+      <entry>
+       <para>
+        Same as <literal>.**</literal>, but with filter over nesting
+        level of JSON hierarchy. Levels are specified as integers.
+        Zero level corresponds to current object.  This is a
+        <productname>PostgreSQL</productname> extension of the SQL/JSON
+        standard.
+       </para>
+      </entry>
+     </row>
      <row>
       <entry>
        <para>