Add new rule VOG033 to AnalyzerReleases.Unshipped.md

Added a new rule to the `AnalyzerReleases.Unshipped.md` file:
- **Rule ID**: VOG033
- **Category**: Usage
- **Severity**: Info
- **Notes**: UseReadonlyStructInsteadOfStructAnalyzer

src/Vogen/AnalyzerReleases.Unshipped.md

@@ -5,4 +5,5 @@
 
 Rule ID | Category | Severity | Notes
 --------|----------|----------|-------
+VOG033 | Usage | Info | UseReadonlyStructInsteadOfStructAnalyzer