Add debugging documentation

[NiQ1]

Please add some sort of documentation of which debuggers are compatible PSL1GHT applications, and what are the requirements (I assume a DEX console would be required).
Currently the only mention of debugging is using stdout prints.

If there is no possible way of debugging properly without using leaked tools (i.e. ProDG) or it is not possible at all, I think this should be mentioned explicitly so developers don't spend time looking for something that doesn't exist.

[Fancy2209]

The only way to debug right now is using gdb with RPCS3
To do this you gotta:

1. Enable Debug Settings
2. Disable "Automatically start games after boot" on Debug Settings
3. Open your app, make sure it's an unstripped elf that has been ran trough sprxlinker. After this you'll see RPCS3 will say Resume instead of Play
4. After this, do ppu-gdb PATH/TO/ELF and when on the GDB prompt, do target remote :2345
   And that's it