Update README.md

Signed-off-by: Michael Egger <[email protected]>

README.md

@@ -1,10 +1,18 @@
 # Portage Lostfiles
-A simple script to identify files not tracked by [Portage](https://wiki.gentoo.org/wiki/Portage) package manager.
+A simple script to identify files not tracked by
+[Portage](https://wiki.gentoo.org/wiki/Portage) package manager.
+This package can be installed via the [GURU overlay](https://wiki.gentoo.org/wiki/Project:GURU).
+
+## Why
+Over time a large number of untracked files can accumulate,
+either created manually or leftovers from uninstalled packages,
+which can result in subtle bugs or misconfigurations.
 
 ## Notes
 Symlinks are not reported as lost as long as the link target exists and is tracked.
 
-Some common paths are not reported (e.g.: `/etc/group`, `/etc/machine-id`, ...). The full whitelist is defined by `WHITELIST` in `lostfiles.py`.
+Some common paths are not reported (e.g.: `/etc/group`, `/etc/machine-id`, ...),
+those are defined in `IGNORED_PATHS` and `PKG_PATHS` in `lostfiles.py`.
 
 ## Usage
 ```bash
@@ -25,4 +33,5 @@ $ ./lostfiles.py -p /lib -p /lib32 -p /lib64
 ```
 
 ## Dependencies
-* python3.6+
+* python >= 3.8
+* portage >= 3, < 4