feat(apple): Add documentation for metrics

[philprime]

DESCRIBE YOUR PR

Adds documentation for the new feature Metrics on Apple platforms, based on the JavaScript and Python documentation.

IS YOUR CHANGE URGENT?

Help us prioritize incoming PRs by letting us know when the change needs to go live.

• [ ] Urgent deadline (GA date, etc.):
• [X] Other deadline: Q1 FY27
• [ ] None: Not urgent, can wait up to 1 week+

SLA

• Teamwork makes the dream work, so please add a reviewer to your PRs.
• Please give the docs team up to 1 week to review your PR unless you've added an urgent due date to it. Thanks in advance for your help!

PRE-MERGE CHECKLIST

Make sure you've checked the following before merging your changes:

• [ ] Checked Vercel preview for correctness, including links
• [ ] PR was reviewed and approved by any necessary SMEs (subject matter experts)
• [ ] PR was reviewed and approved by a member of the Sentry docs team

Closes https://linear.app/getsentry/issue/COCOA-1088/metrics-add-documentation-for-feature Closes https://github.com/getsentry/sentry-cocoa/issues/7045

[linear[bot]]

COCOA-1088 [Metrics] Add documentation for feature

[vercel[bot]]

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Project	Deployment	Review	Updated (UTC)
sentry-docs	Ready	Preview, Comment	Dec 15, 2025 4:11pm

1 Skipped Deployment

Project	Deployment	Review	Updated (UTC)
develop-docs	Ignored		Dec 15, 2025 4:11pm