BEAM-1857 : CHANGES.md entry for 2.38.0
BEAM-1857 : CHANGES.md entry for 2.38.0

chamikaramj/beam,lukecwik/incubator-beam,chamikaramj/beam,chamikaramj/beam,chamikaramj/beam,apache/beam,apache/beam,chamikaramj/beam,lukecwik/incubator-beam,lukecwik/incubator-beam,lukecwik/incubator-beam,lukecwik/incubator-beam,apache/beam,apache/beam,chamikaramj/beam,apache/beam,apache/beam,chamikaramj/beam,lukecwik/incubator-beam,chamikaramj/beam,apache/beam,lukecwik/incubator-beam,lukecwik/incubator-beam,apache/beam,apache/beam,lukecwik/incubator-beam,chamikaramj/beam,apache/beam,lukecwik/incubator-beam,apache/beam,chamikaramj/beam