Update CHANGELOG.md

Added entries for changes to date.

Author: rob-ross

CHANGELOG.md

@@ -1,2 +1,9 @@
-# FIRST!
+### 2025-07-08 
+Unit testing
+- Refactored lexer, parser, and evaluator tests to use JSON file format similar to cts.json.
+- Implemented tests of lexer, parser, and evaluator for all examples and tables 2-18 in RFC 9535.
+- Completed testgen.py to automate the creation of JSON test files for the above.
+  
 
+### 2025-06-24
+- Initial commit from local sources after 3-months of development.