Explain search more in documentation / README

**is your feature request related to a problem? Please describe.**
A proper search docu would be nice so an enduser knows what the search actually can and can't do and why for example `( name like *.mp3 ) and ( name like *.mp3-* )` returns happy results but how dare you do `( name like *.mp3-*.mp3) ` - that won't return a thing! (as you may have guessed I just want to remove these duplicate mp3s...) .

Also more generally a plain old regex file search would be awesome, as SQL LIKE statement limitations are not as familiar to most people as regex (at least in my crowd).

**Describe the idea / solution you'd like**
Explain search functionality more than with a few examples.