Add feature for trestle author docs for validating certain documents under it

[AleJo2995]

Describe the bug

Let´s say we have a task name called a. Under a there are 3 folders with documents each b, c, d. Let´s say I only want to validate the documents that are under folder b, not c or d. Right now this is not possible as the trestle author docs is validating all folders under a, not just b. There needs to be a way to parametrize just the folder I want to validate.

To Reproduce

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1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior

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Environment

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