message: Added comment expaining sharding property of ReplaceInst
diff: @@ -314,6 +314,8 @@ class HloComputation {
  // Replace old instruction with new instruction. Updates uses and root
  // instruction. Removes old instruction from computation. Precondition:
  // old_instruction and new_instruction must have the compatible shapes.
  + // If |new_instruction| doesn't have any sharding information it will
  + // recieve the sharding information of |old_instruction|.
  Status ReplaceInstruction(HloInstruction* old_instruction,
  HloInstruction* new_instruction);
  