{Documentation} MPS - Update projectaria-mps changelog

Summary:
The public ARK MPS changelog stopped at `projectaria-mps` `1.2.0`, while PyPI now lists `1.2.3` as the latest release. That leaves users checking the static docs without the patch-release history they see from the package index.

This updates the MPS changelog with patch releases `1.2.1`, `1.2.2`, and `1.2.3`. Each new entry uses the requested release-note text: `Minor bug fixes`; no APIs, package metadata, examples, or runtime behavior change.

Reviewers should check two things: (1) the release order stays newest-first, and (2) the terse patch notes are intentional for these point releases.

```lang=mermaid
flowchart TD
  A[PyPI releases through 1.2.3] --> B[ARK MPS changelog]
  B --> C[Public docs show 1.2.1, 1.2.2, and 1.2.3]
```

Current release notes need current versions.

___

Differential Revision: D110802622

fbshipit-source-id: 002296aae282f7d5fe9681f955f305895c62b966

Author: nrraina

website/docs-ark/mps/changelog.mdx

@@ -5,6 +5,21 @@ title: Changelog
 
 # Changelog
 
+---
+## Version 1.2.3
+- Minor bug fixes
+
+
+---
+## Version 1.2.2
+- Minor bug fixes
+
+
+---
+## Version 1.2.1
+- Minor bug fixes
+
+
 ---
 ## Version 1.2.0
 - Add Multi-SLAM support for Aria Gen 2 recordings