Improve step5 (docs and frontend)

[tkat0]

What

• document/step5.{en,ja}.md
  • Fix typo and add some notes for React
  • Change recommended node version from v14 to v16
  • To avoid environmental troubles as node v14 and later sometimes behave differently
• typescript/*
  • Change to reload after listing complete
  • I guess the behavior before the change confuses trainees. I thought having the trainees fix it but React is out of scope in this training. So I fixed it.

CHECKS :warning:

Please make sure you are aware of the following.

• [x] **The changes in this PR doesn't have private information

[tkat0]

Thank you for your review!