Add CHANGELOG entry for linting-extensions (#46109)

Author: alzimmermsft

sdk/tools/linting-extensions/CHANGELOG.md

@@ -1,11 +1,10 @@
 # Release History
 
-## 1.0.0-beta.1 (Unreleased)
+## 1.0.0-beta.1 (2025-07-22)
 
-### Features Added
-
-### Breaking Changes
+Initial release of the SDK Linting Extensions.
 
-### Bugs Fixed
+### Features Added
 
-### Other Changes
+- Added Checkstyle extensions for enforcing SDK guidelines.
+- Added RevApi extensions for API compatibility checks.