Made flatpak optional and some code cleanup (#11)

* Add PKGBUILD

* This is a basic implementation that works.

* I know what I am doing. Trust me.

* Made flatpak optional and code cleanup

* fixed issue with useless error msg

---------

Co-authored-by: FUH22860 <101731147+FUH22860@users.noreply.github.com>

README.md

@@ -13,18 +13,23 @@ Before installing, please edit the config and configure it to your liking.
 ```bash
 make install
 ```
+
+You will likely have to
+
 ## Usage
 
 ```
 Usage: update [OPTION]
 
 options:
-no flag        same as -a
+no flag        same as -p
 -f             updates using flatpak update only
 -p             updates using a pacman-wrapper only
 -a             updates using flatpak update and a pacman-wrapper
 -g             shutdowns the computer afterwards (needs to be the last or only option to work properly)
 -r             reboots the computer afterwards (needs to be the last or only option to work properly)
+--help         displays this message
+-P, --preview  shows a preview of which pkg's will be updates
 ```
 
 ## Contributing