Add TimescaleDB 2.28.x to PostgreSQL compatibility matrix

[atovpeko]

Describe your changes

Adds TimescaleDB 2.28.x to the PostgreSQL compatibility matrix and sharpens the PostgreSQL 15 deprecation note, per the TimescaleDB 2.28.0 release (timescale/timescaledb#10010).

• Adds a 2.28.x row to the matrix: supports PostgreSQL 16, 17, and 18, and is the final minor version to support PostgreSQL 15.
• Updates the deprecation callout to be version-specific: PostgreSQL 15 support is dropped in 2.29.0, while patch releases in the 2.28.x cycle continue to support it. Replaces the previous date-only ("June 2026") wording.

Affected pages

• /deploy/self-hosted/upgrades/major-upgrade
• /deploy/self-hosted/upgrades/minor-upgrade
• /deploy/self-hosted/upgrades/upgrade-pg
• /deploy/tiger-cloud/tiger-cloud-aws/upgrades
• /deploy/tiger-cloud/tiger-cloud-azure/upgrades
• /get-started/choose-your-path/supported-platforms

Related Issues

Issue: https://linear.app/tigerdata/issue/EDU-136

Checklist before requesting a review

• - This is ready for review. If not, raise as a draft PR
• - I have reviewed my changes.
• - I have confirmed the content is technically accurate.
• - I have tested any code that is added or updated on the latest available version.
• - I have confirmed the content is free of typos or grammar errors.
• - I have verified all images and videos are clear and match production (or dev for unreleased features).
• - This references a feature that is public. If not, add a note and we can schedule the merge for after the feature release.

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Project	Deployment	Actions	Updated (UTC)
tiger-data-docs	Ready	Preview, Comment	Jun 11, 2026 10:32am

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