Add documentation for Arbitrary and Debug trait for Custom types, add example

[lukacan]

Please merge PR #135 first, as this PR updates the documentation.

Currently, the framework lacks documentation on using the Arbitrary and Debug traits with custom types as instruction data parameters.

This PR includes:

• A new section that explains how to use the mentioned traits.
• A practical demonstration, "fuzz example 4," illustrating the described usage.

Note: fuzz_example4 link points to the develop branch, so this link will be active once the example is in the develop branch