New Function: set_exception_handler

[roberto-butti]

What

Add a new method documentation file for a new PHP function in the src/content/docs directory.
The instructions about defining the file's name are documented in the CONTRIBUTING.md file.

Description

Function name: example set_exception_handler()
Function description: it allows you to declare a callback function that will handle all uncaught exceptions.
File name: example src/content/docs/01-system/16-sys-set-exception-handler.md

Checklist

• create the file with the proper name
• create the documentation of the function
• write example in examples directory
• execute pint examples
• commit and open the PR.

Must read:

• https://github.com/roberto-butti/some-drops-of-php/blob/main/HACKTOBERFEST.md
• https://github.com/roberto-butti/some-drops-of-php/blob/main/CONTRIBUTING.md