[KV] Adding new info on metric/analytics API

[Oxyjun]

DO NOT MERGE

Summary

Migrating PR from before the dev-docs migration. This relates to https://github.com/cloudflare/cloudflare-docs/pull/15918

Adding:

1. New chapter on "Metrics and analytics" under a new "Observability" navigation tab.
2. "Changelog" under "Platform" navigation tab.
3. "kv.yaml" file where changelogs live.

Note:

This PR is high-priority. Iterative improvements can be made in future pushes.

No material changes have been made to this PR regarding content - only the required syntax has been changed to conform the PR to meet docs standards.

Screenshots (optional)

Documentation checklist

• [x] The documentation style guide has been adhered to.
• [ ] If a larger change - such as adding a new page- an issue has been opened in relation to any incorrect or out of date information that this PR fixes.
• [ ] Files which have changed name or location have been allocated redirects.

[cloudflare-workers-and-pages[bot]]

Deploying cloudflare-docs with    Cloudflare Pages

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[github-actions[bot]]

Files with changes (up to 15)

Original Link	Updated Link
https://developers.cloudflare.com/kv/observability/metrics-analytics/	https://jun-kv-metrics-and-analytics.cloudflare-docs-7ou.pages.dev/kv/observability/metrics-analytics/
https://developers.cloudflare.com/kv/platform/changelog/	https://jun-kv-metrics-and-analytics.cloudflare-docs-7ou.pages.dev/kv/platform/changelog/
https://developers.cloudflare.com/kv/observability/index/	https://jun-kv-metrics-and-analytics.cloudflare-docs-7ou.pages.dev/kv/observability/index/

[thomasgauvin]

This PR should not be merged until we are ready to announce KV analytics

[thomasgauvin]

We will merge when the dashboard is pushed and publicly available