docs(upgrade): add documentation for upgrade command

[betegon]

Summary

Adds missing documentation for the sentry upgrade command. The upgrade command was added in #132 but docs were not included.

Changes

New doc at docs/src/content/docs/commands/upgrade.md covering:

• Basic usage and examples
• --check and --method flags
• Installation method auto-detection
• Sample output

Test Plan

Preview the docs site locally with bun run dev in docs/.

[github-actions]

Semver Impact of This PR

🟢 Patch (bug fixes)

📋 Changelog Preview

This is how your changes will appear in the changelog.
Entries from this PR are highlighted with a left border (blockquote style).

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New Features ✨

• (upgrade) Add self-update command by betegon in #132

Bug Fixes 🐛

• (telemetry) Capture command errors to Sentry by betegon in #145
• Update docs URL in help output by betegon in #149

Documentation 📚

• (upgrade) Add documentation for upgrade command by betegon in #152

• Update README and AGENTS.md by betegon in #148

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_{🤖 This preview updates automatically when you update the PR.}

[github-actions]

PR Preview Action v1.8.1
🚀 View preview at https://cli.sentry.dev/pr-preview/pr-152/
Built to branch gh-pages at 2026-02-01 17:54 UTC. Preview will be ready when the GitHub Pages deployment is complete.

[github-actions]

Codecov Results 📊

✅ Patch coverage is 100.00%. Project has 2008 uncovered lines.
✅ Project coverage is 68.08%. Comparing base (base) to head (head).

Files with missing lines (26)

File	Patch %	Lines
human.ts	31.87%	⚠️ 682 Missing
resolve-target.ts	20.82%	⚠️ 251 Missing
oauth.ts	25.10%	⚠️ 194 Missing
upgrade.ts	33.33%	⚠️ 166 Missing
api-client.ts	71.60%	⚠️ 146 Missing
resolver.ts	3.23%	⚠️ 120 Missing
errors.ts	5.94%	⚠️ 95 Missing
migration.ts	47.44%	⚠️ 82 Missing
upgrade.ts	38.78%	⚠️ 60 Missing
api.ts	89.80%	⚠️ 47 Missing
seer.ts	75.54%	⚠️ 45 Missing
seer.ts	79.87%	⚠️ 30 Missing
preload.ts	39.02%	⚠️ 25 Missing
detector.ts	87.79%	⚠️ 16 Missing
schema.ts	64.10%	⚠️ 14 Missing
auth.ts	94.78%	⚠️ 7 Missing
utils.ts	97.59%	⚠️ 4 Missing
index.ts	95.06%	⚠️ 4 Missing
colors.ts	91.84%	⚠️ 4 Missing
telemetry.ts	97.16%	⚠️ 4 Missing
env-file.ts	97.17%	⚠️ 3 Missing
sentry-urls.ts	82.35%	⚠️ 3 Missing
alias.ts	98.56%	⚠️ 2 Missing
project-aliases.ts	97.40%	⚠️ 2 Missing
java.ts	97.22%	⚠️ 1 Missing
parser.ts	98.63%	⚠️ 1 Missing

Coverage diff

@@            Coverage Diff             @@
##          main       #PR       +/-##
==========================================
+ Coverage    68.08%    68.08%        —%
==========================================
  Files           53        53         —
  Lines         6290      6290         —
  Branches         0         0         —
==========================================
+ Hits          4282      4282         —
- Misses        2008      2008         —
- Partials         0         0         —

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