Revise home page text, remove unnecessary docs, make new category for status code docs

[josh-wong]

Description

This PR updates links, removes unnecessary docs, and makes status code docs a category in the sidebar navigation. The docs that have been removed are ones that we had as indexes since our previous docs site didn't have collapsible categories in the sidebar navigation.

Related issues and/or PRs

N/A

Changes made

• Revised the text in the Cards on the home page.
• Added status code docs to a collapsible category in the sidebar navigation.
• Removed unnecessary index docs.

Checklist

The following is a best-effort checklist. If any items in this checklist are not applicable to this PR or are dependent on other, unmerged PRs, please still mark the checkboxes after you have read and understood each item.

• I have updated the side navigation as necessary.
• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation to reflect the changes.
• Any remaining open issues linked to this PR are documented and up-to-date (Jira, GitHub, etc.).
• My changes generate no new warnings.
• Any dependent changes in other PRs have been merged and published.

Additional notes (optional)

N/A