docs(matcher): add v2.3 upgrade guide

[gandalf-at-lerian]

Summary

• Adds the retroactive minor upgrade guide for from to .
• Patch-only upgrade docs remain ignored, per task scope.

Requested by: @guimoreirar

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 43ed15fa-9820-44c3-8f60-75d392f573b5

📥 Commits

Reviewing files that changed from the base of the PR and between c88fb45 and 4c81ebf.

📒 Files selected for processing (1)

• charts/matcher/docs/UPGRADE-2.3.md

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Walkthrough

Adds an upgrade guide for the matcher Helm chart documenting changes in 2.3.0-beta.2, including probe configurability, readiness path defaulting to /readyz, modified chart files, migration steps, verification commands, and example Helm commands.

Changes

Matcher Chart Upgrade Guide

Layer / File(s)	Summary
Matcher chart upgrade documentation charts/matcher/docs/UPGRADE-2.3.md	New upgrade guide documents the release of matcher chart 2.3.0-beta.2, covering probe configurability and readiness path default change, lists modified chart/templates/values files, and provides step-by-step migration and verification commands plus example helm diff upgrade and helm upgrade commands.

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_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@charts/matcher/docs/UPGRADE-2.3.md`:
- Around line 47-52: The migration guide's Step 2 in "Migration steps" conflicts
with the "Configuration changes" section which reports "No direct values.yaml
key changes detected"; update Step 2 in UPGRADE-2.3.md to remove or qualify the
advice to "Add any required new values..., especially secrets, configmaps,
probes, ingress, and service settings" — either remove the parenthetical list or
change it to conditional language (e.g., "If your environment requires new keys,
add them...") and add a short note referencing the "Configuration changes"
summary so readers know no values.yaml changes are required for this release
unless they have custom overrides.
- Line 3: The table of contents line is concatenated into one long string ("-
**[Overview](`#overview`)**- **[Version changes](`#version-changes`)**..."); split
it so each topic is on its own markdown line (e.g., "-
**[Overview](`#overview`)**" on one line, "- **[Version
changes](`#version-changes`)**" on the next, etc.) to restore proper TOC
formatting and readability, ensuring consistent leading hyphen and spacing for
each entry.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 5a35971a-f9c7-49ae-8fe6-1a7cb68becda

📥 Commits

Reviewing files that changed from the base of the PR and between 3766751 and c88fb45.

📒 Files selected for processing (1)

• charts/matcher/docs/UPGRADE-2.3.md