[MINOR] Update PR template with documentation update

[yihua]

Change Logs

As above. The author of PRs should put up docs updates as part of their contribution. The author should create a Jira for the docs and link them in the PR description.

Impact

Risk level: none

Contributor's checklist

• [ ] Read through contributor's guide
• [ ] Change Logs and Impact were stated clearly
• [ ] Adequate tests were added if applicable
• [ ] CI passed

[hudi-bot]

CI report:

• 228dee0f746fbd9630c6e5f87174837263b7467f Azure: SUCCESS

Bot commands

@hudi-bot supports the following commands:

• @hudi-bot run azure re-run the last Azure build