Update .gitignore and enhance test documentation for coverage reporting

- Add /bench/backups, /target/, cobertura.xml, and tarpaulin-report.html to .gitignore to prevent tracking of generated files.
- Update test.md to include instructions for running tests and generating coverage reports using cargo tarpaulin.

cli-bin/tests/test.md

@@ -69,4 +69,10 @@ or
 
 ```bash
 ./run_all_tests.sh
+```
+
+to see test coverage run:
+
+```bash
+cargo tarpaulin --out Html
 ```