PG 10 release notes:  update PL/Tcl functions item
PG 10 release notes:  update PL/Tcl functions item

Update attribution of PL/Tcl functions item from Jim Nasby to Karl
Lehenbauer.

Reported-by: Jim Nasby

Discussion: https://postgr.es/m/ed42f3d6-4251-dabc-747f-1ff936763b2b@nasby.net

Backpatch-through: 10

xinzweb/gpdb,lisakowen/gpdb,50wu/gpdb,xinzweb/gpdb,xinzweb/gpdb,lisakowen/gpdb,lisakowen/gpdb,lisakowen/gpdb,greenplum-db/gpdb,50wu/gpdb,adam8157/gpdb,greenplum-db/gpdb,xinzweb/gpdb,adam8157/gpdb,greenplum-db/gpdb,50wu/gpdb,50wu/gpdb,adam8157/gpdb,adam8157/gpdb,adam8157/gpdb,lisakowen/gpdb,50wu/gpdb,xinzweb/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,lisakowen/gpdb,lisakowen/gpdb,adam8157/gpdb,50wu/gpdb,greenplum-db/gpdb,xinzweb/gpdb,lisakowen/gpdb,adam8157/gpdb,adam8157/gpdb,xinzweb/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,50wu/gpdb,xinzweb/gpdb,50wu/gpdb