docs: add JSONB containment example of a key and empty object
Backpatch through 9.5
Branch
------
REL9_5_STABLE
Details
-------
http://git.postgresql.org/pg/commitdiff/c86555fc80bbbf276de42f43761991212b713575
Modified Files
--------------
doc/src/sgml/json.sgml | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)