[DOCS] Self-nestings listed twice

[ebeahan]

Description of the issue:

Self-nestings (a field set reused within that same field set) show up in the Field sets that can be nested under <field set> heading under Field Reuses, and also show up under the The <field set> fields are expected to be nested at:.

Should self-nestings should show up under Field sets that can be nested under <field set> only and not with other "foreign" reuses?

Example

user.changes, user.target, and user.effective are listed twice. The wording of the text in the first list is correct; for example, we do expect user to be nested as user.effective.