Fix /e entry in /?

[kazarmy]

Your checklist for this pull request

• I've read the guidelines for contributing to this repository
• I made sure to follow the project's coding style
• I've documented or updated the documentation of every function and struct this PR changes. If not so I've explained why.
• I've added tests that prove my fix is effective or that my feature works (if possible)
• I've updated the rizin book with the relevant information (if needed)

Detailed description

This pr fixes the /e entry in /? to be more helpful. This doesn't mean that the /e regex search works well, but it's a start.

Test plan

The change makes sense. All builds are green.

Closing issues

...