…roles (#150)

* docs: Add docs for error when updating a user with non-existent roles

* docs: Move 400 response example to the update roles request

* docs: Fix grammar

* docs: Add separate headers for all responses

* docs: Change comments to descriptions and add body tags

* Revert "docs: Change comments to descriptions and add body tags"

This reverts commit eba9380.

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Co-authored-by: Sam Ford <sam.ford@acrolinx.com>

…ex/root API (#158)

Co-authored-by: Sam Ford <sam.ford@acrolinx.com>

* docs: Add staffUser, idpUser and rolesSetByIdp properties to user json

* docs: Add 400 response for updating a user's roles when their roles are managed by their IDP

* docs: Add idpUser, staffUser and rolesSetByIdp properties to data structures

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Co-authored-by: Sam Ford <sam.ford@acrolinx.com>