[GSoC] Add more builtin patterns for userdiff: Add builtin patterns for Verilog

Hello everyone,

I am new to the Git community and would like to contribute. I noticed that there are no builtin patterns for the Verilog language in `userdiff.c`. Since I recently worked on a project involving Verilog, I decided to add support for it.

Below is a summary of my changes:

1. Added Verilog builtin patterns to `userdiff.c`.
2. Updated the documentation to reflect the new patterns.

If you have any suggestions or feedback, please let me know. I would greatly appreciate your guidance to avoid any mistakes or detours.

Thank you very much!

Best regards,
Hao Chenming