Update UIBuilder related collection documentation

[acoumb]

Description

Updated Umbraco UIBuilder docs about related collections.

Type of suggestion

• Typo/grammar fix
• Updated outdated content
• New content
• Updates related to a new version
• Other

Product & version (if relevant)

Deadline (if relevant)

[sofietoft]

Looks good @acoumb ! 🙌

Should we add this to version 14 and 15 as well?

[acoumb]

Yes, please.

[sofietoft]

Perfect. I'll take care of that after it's been merged.

Thanks again!

[jemayn]

Hey @acoumb

Thanks for writing this documentation!
Any chance there could be an explanation of what the string relationAlias param does in the GetRelationsByParentIdImpl method?

I see it is not currently in use in your example 🙂

[acoumb]

Hi,

It's the relation alias you define here:

    relationConfig
        .SetAlias("studentsCourses")
        .SetJunction<StudentCourse>(x => x.StudentId, y => y.CourseId);