Coverage-guided fuzzing Documentation

Full context in parent epic

Documentation should cover at a minimum:

1. Description of what fuzzing is.
2. Description of the problem fuzzing solves.
3. Technical instructions for adding our fuzzer to a project.
   1. Screenshots are required for this.
4. Technical instructions for understanding the results from fuzzing.
   1. Screenshots are required for this.
5. An example of walking through a project and using the fuzzer.

The following page may contain information related to upcoming products, features and functionality. It is important to note that the information presented is for informational purposes only, so please do not rely on the information for purchasing or planning purposes. Just like with all projects, the items mentioned on the page are subject to change or delay, and the development, release, and timing of any products, features, or functionality remain at the sole discretion of GitLab Inc.