You should define the knowledge and skill set of your target audience before starting your documentation. You can then use this information to avoid wasting time explaining information your audience already knows.
Just as stories are used to define software, learning objectives can be written using a standard template: As a [user] of the [solution] I [know a specific piece of information] or can [perform a specific task]
For each learning objective, you should:
- Identify what your audience should know and be able to do after they have read the documentation.
- Use that information to create a list of learning objectives.