[doc] Update example-parameter-server.rst (#3773)
[doc] Update example-parameter-server.rst (#3773)


richardliaw/ray,ray-project/ray,robertnishihara/ray,robertnishihara/ray,stephanie-wang/ray,atumanov/ray,richardliaw/ray,pcmoritz/ray-1,pcmoritz/ray-1,ray-project/ray,ujvl/ray-ng,pcmoritz/ray-1,stephanie-wang/ray,robertnishihara/ray,ujvl/ray-ng,robertnishihara/ray,atumanov/ray,stephanie-wang/ray,ray-project/ray,atumanov/ray,richardliaw/ray,atumanov/ray,pcmoritz/ray-1,stephanie-wang/ray,ray-project/ray,pcmoritz/ray-1,robertnishihara/ray,atumanov/ray,ray-project/ray,richardliaw/ray,richardliaw/ray,stephanie-wang/ray,robertnishihara/ray,richardliaw/ray,stephanie-wang/ray,stephanie-wang/ray,stephanie-wang/ray,robertnishihara/ray,atumanov/ray,robertnishihara/ray,richardliaw/ray,ray-project/ray,richardliaw/ray,ujvl/ray-ng,atumanov/ray,ujvl/ray-ng,pcmoritz/ray-1,atumanov/ray,pcmoritz/ray-1,stephanie-wang/ray,robertnishihara/ray,ray-project/ray,ray-project/ray,pcmoritz/ray-1