Docs: add missing prerequisite for installation

[dkleinF5]

Proposed changes

Checklist

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Footnotes

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[dkleinF5]

I have hereby read the F5 CLA and agree to its terms

[JTorreG]

There is a TODO label

[ADubhlaoich]

Generally LGTM: approval pending feedback.

Please run the linting tools on this branch, which can be executed automatically with pre-commit.

[ADubhlaoich]

Some more minor changes for content flow and formatting.

[ADubhlaoich]

I have already given this feedback and it has not been addressed: there has been unnecessary detail added to every single set of pre-requisites.

• Download the SSL certificate and private key associated with your F5 NGINX App Protect WAF subscription from the MyF5 Customer Portal.
  Docker registry credentials are needed to access private-registry.nginx.com

These are not pre-requisites: they are instructions, and they are redundant instructions.

Immediately after the user finishes reading the "Before you begin" section, they are explicitly guided through the steps involved in downloading and configuring the credentials needed to follow the rest of the document.

[ADubhlaoich]

This is an excessive use of consecutive call-outs.

Call-outs are intended to draw the user's attention to something highly specific they need to take extra care of: if you over-use them, everything looks important, and nothing looks important as a result.

1. The content of the first can be replaced with an anchor link to "skip" the unnecessary section for OSS users
2. The second call-out is fine, and a good example of how call-outs should primarily be used
3. The third call-out is redundant, because the instructions involving NGINX Plus guide the user towards using a JWT file: there's no point telling someone they will need to do something if you're already expecting them to do it as part of the instructions

[dkleinF5]

I have already given this feedback and it has not been addressed: there has been unnecessary detail added to every single set of pre-requisites.

• Download the SSL certificate and private key associated with your F5 NGINX App Protect WAF subscription from the MyF5 Customer Portal.
  Docker registry credentials are needed to access private-registry.nginx.com

These are not pre-requisites: they are instructions, and they are redundant instructions.

Immediately after the user finishes reading the "Before you begin" section, they are explicitly guided through the steps involved in downloading and configuring the credentials needed to follow the rest of the document.

@ADubhlaoich Are you able to speak with Aviv Dahan about this. This is something product requested.