Update naas docs to call out expectations on network attachments

[puneetsarna]

We have cases where users will have network
attachments with a list of projects allowed on it. We are making changes to the service to handle
this better and float the error to the user.

This change calls out what the user sees and
should do in a situation where flow they have
project allowlists on the network attachment.

Proposed changes

Checklist

Before sharing this pull request, I completed the following checklist:

• I read the Contributing guidelines
• My branch adheres to the Git conventions
• My content changes adhere to the F5 NGINX Documentation style guide
• If my changes involve potentially sensitive information¹, I have assessed the possible impact
• I have waited to ensure my changes pass tests, and addressed any discovered issues

Footnotes

1. Potentially sensitive information includes personally identify information (PII), authentication credentials, and live URLs. Refer to the style guide for guidance about placeholder content. ↩

[github-actions]

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[ADubhlaoich]

Generally LGTM from a docs style perspective

[amudukutore]

@puneetsarna - I'm okay committing these changes as is but would prefer to incorporate the minor suggestions on calling out some of these changes more explicitly (it's up to you). I'm approving this either way.