Docs feedback: Improve "Review a merge request" tutorial

• Start this issue's title with Docs: or Docs feedback:.

Problem to solve

User feedback:

I am looking for the submit review button so my comment is not pending. This is incredibly hard to use and frankly shows poor design

Further details

On the Tutorial: Review a merge request page, the location of the Your review button, where you can Submit review is not mentioned in the tutorial.

Proposal

Update the tutorial so that it's easy for users to understand where the Your review widget is located.

Other links/references

• https://gitlab.com/gitlab-org/gitlab/-/issues/564995