docs: Add coverage reporting section to CONTRIBUTING.md

Author: GeekMasher

CONTRIBUTING.md

@@ -65,6 +65,60 @@ To test the CodeQL libraries and queries, you can run the following command:
 ./scripts/run-tests.sh
 ```
 
+### Coverage Reporting
+
+The project includes a coverage script to track CodeQL query coverage and generate reports. The script analyzes all available queries and provides detailed coverage statistics.
+
+#### Running the Coverage Script
+
+To update coverage data and generate a report:
+
+```bash
+python scripts/coverage.py
+```
+
+This will:
+- Load the existing `.coverage.json` file
+- Run `codeql resolve queries` to discover all available queries
+- Update the coverage data with query metadata
+- Generate a markdown coverage report
+- Update the README.md file with the latest coverage statistics
+
+#### Coverage Script Options
+
+The coverage script supports several command-line options:
+
+```bash
+# Generate only markdown output (useful for CI/CD)
+python scripts/coverage.py --markdown-only
+
+# Update coverage data but skip README.md update
+python scripts/coverage.py --no-readme-update
+
+# Show help and available options
+python scripts/coverage.py --help
+```
+
+#### Coverage Report Features
+
+The generated coverage report includes:
+
+- **Coverage Badge**: Dynamically colored based on coverage percentage
+- **Summary Statistics**: Total queries, covered queries, coverage percentage
+- **Category Breakdown**: Coverage by query category (Security, Diagnostics)
+- **CWE Analysis**: Coverage by Common Weakness Enumeration categories
+- **Timestamp**: When the report was last generated
+
+#### Understanding Coverage Data
+
+The coverage script tracks:
+- **Total Queries**: All queries discovered in `ql/src/`
+- **Covered Queries**: Queries that have associated tests (initially 0, updated as tests are added)
+- **Categories**: Query categories like `security` and `diagnostics`
+- **CWE Categories**: Security queries mapped to Common Weakness Enumeration identifiers
+
+To mark a query as "covered", you'll need to create corresponding test files in the `ql/test/` directory structure.
+
 ## Resources
 
 - [How to Contribute to Open Source](https://opensource.guide/how-to-contribute/)