docs: nest soft-delete section under Advanced quota check and trim verbosity

[achandmsft]

Problem

The Free quota held by soft-deleted Cognitive Services accounts section in README.md is verbose (~55 lines) and lives as a sibling of Advanced: check Claude quota & capacity programmatically, even though both sections cover quota topics and read better together. The troubleshooting table also re-explains the same content in a long inline row that duplicates what the linked section already says.

Proposal

• Nest the soft-delete section inside the existing Advanced: check Claude quota & capacity programmatically <details> block so the two quota topics live together.
• Trim it to a short fix + caveats (list/purge commands kept; long prose removed).
• Match the README's established <summary><strong>...</strong></summary> pattern for a "main section heading, collapsed" feel.
• Tighten the troubleshooting row that re-explained the same thing to a one-liner pointing at the section.
• Preserve the existing anchor id #free-quota-held-by-soft-deleted-accounts so all cross-links keep working (referenced 3× from the troubleshooting table).

Outcome

• Net -17 lines in README.md (+40 / -57).
• Single source of truth for soft-delete remediation, co-located with the rest of the quota guidance.
• All existing cross-links continue to resolve.

PR: see linked PR for the change.