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

[achandmsft]

Summary

Nests the Free quota held by soft-deleted accounts section inside the existing Advanced: check Claude quota & capacity programmatically <details> block, and trims it to a short fix + caveats. Also tightens the troubleshooting row that re-explained the same content.

Fixes #34.

Why

• Both sections cover quota; co-locating them gives readers one place to look when a deploy fails with 715-123420 / InsufficientQuota.
• The original soft-delete block was ~55 lines of prose. The fix is really just list → purge, plus two caveats.
• The troubleshooting row duplicated the fix; the linked section now owns it.

Changes

• README.md
  • Removed the standalone <details id="free-quota-held-by-soft-deleted-accounts"> block from between the Preflight and Advanced quota details.
  • Added a concise nested <details> (same anchor id) at the bottom of <details id="advanced-check-claude-quota--capacity-programmatically">.
  • Trimmed the "Quota looks full but you have no live deployments" troubleshooting row to a one-liner pointing at the section.

Cross-link compatibility

Anchor id #free-quota-held-by-soft-deleted-accounts is preserved, so the three existing cross-links from the troubleshooting table still resolve.

Diff stat

README.md | 97 ++++++++++++++++++++++++++-------------------------------------
1 file changed, 40 insertions(+), 57 deletions(-)

Net -17 lines.

Test plan

• Render README.md on GitHub and confirm:
  • The nested <details> expands/collapses correctly inside its parent.
  • The three troubleshooting cross-links still scroll to the soft-delete section.
• No content lost — list, purge-one, parallel purge (pwsh + bash), and re-check command are all preserved (just compressed).