Update Software Catalog setup landing page and add correlation requirements

[domalessi]

What does this PR do? What is the motivation?

https://datadoghq.atlassian.net/browse/DOCS-12128

This PR does the following:

• Fleshes out the landing page for Software Catalog Setup
  • Some of these details exist already in subpages, but we wanted to provide a consolidated list of data sources that users can reference when setting up their Software Catalogs.
  • I'm torn on the formatting. Right now, each section is formatted in the following manner: header - nextlinks - details. I kept the nextlinks in there and put them immediately under the headers so that users could super easily navigate to the detailed Setup pages. The details underneath the nextlink sections are meant to help flesh out the picture for those interested without going into excessive detail or re-documenting everything already in individual Setup child pages.
• Adds "correlation requirements" to the page describing autodiscovery from APM

Merge instructions

Merge readiness:

• Ready for merge

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Additional notes

[github-actions]

Preview links (active after the build_preview check completes)

Modified Files

• https://docs-staging.datadoghq.com/domalessi/software-catalog-datasources/internal_developer_portal/software_catalog/set_up/
• https://docs-staging.datadoghq.com/domalessi/software-catalog-datasources/internal_developer_portal/software_catalog/set_up/discover_entities

[brett0000FF]

Nice work!

Re: your note on formatting, I think flipping the nextlinks to come after the description paragraph would improve the reading flow by giving context first.

A card-style layout could also work here. I've been experimenting with adding header tags to next links to achieve this effect: https://docs.datadoghq.com/opentelemetry/setup/