Launchpad: Reformat doc on using Bugzilla plugin

Background

The formatting of this doc doesn't follow good documentation practices. It contains unnecessary use of emphasis/bold text, has unnecessary numbering to the steps, and possibly other issues.

Task

Without changing the actual content in the doc, fix all formatting issues with the goal of making the doc easier to read.

Note: This is a beginner task. The learning experience is the main outcome. Therefore, AI-assisted submissions will not be accepted.

Doc: https://ubuntu.com/docs/launchpad/user/how-to/work-with-bugs/use-bugzilla-plugin/ GitHub repo: https://github.com/canonical/launchpad-manual