DEVDOCS-6247 - Content Refresh S2S Sales Staff (#925)

- Restructured doc for readability.
- Added descriptive content to endpoints, parameters, and fields.
- Clarified and corrected responses.

<!-- Ticket number or summary of work -->
# [DEVDOCS-6247]


## What changed?
<!-- Provide a bulleted list in the present tense -->
* 

## Release notes draft
<!-- Provide an entry for the release notes using simple, conversational
language. Don't be too technical. Explain how the change will benefit
the merchant and link to the feature.

Examples:
* The newly-released [X feature] is now available to use. Now, you’ll be
able to [perform Y action].
* We're happy to announce [X feature], which can help you [perform Y
action].
* [X feature] helps you to create [Y response] using the [Z query
parameter]. Now, you can deliver [ex, localized shopping experiences for
your customers].
* Fixed a bug in the [X endpoint]. Now the [Y field] will appear when
you click [Z option]. -->
* 

## Anything else?
<!-- Add related PRs, salient notes, additional ticket numbers, etc. -->

ping { @bc-Vince @CNanninga }


[DEVDOCS-6247]:
https://bigcommercecloud.atlassian.net/browse/DEVDOCS-6247?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ

Author: bc-terra