docs: add initial CHANGELOG.md for version tracking

Created the first CHANGELOG.md file based on "Keep a Changelog" standards. 
Documented both v1.0.0 (initial release) and v1.0.1 (documentation improvement).
This will help track project progress and version changes clearly moving forward.

Update README to reflect renamed SQL script: clinicDB.sql

Updated all references to answers.sql in the README file to clinicDB.sql, following the file rename.
This ensures consistency between the documentation and the actual script name, avoiding confusion for users who follow the setup instructions.