README: Added Tested distributions

README.md

@@ -65,12 +65,17 @@ Currently supported printers:
 -   lj4p
 -   lj5c
 
-At the moment, copy4b and copy5b are not supported.
-
 You can find out more information about printing in general
 at <https://www.fi.muni.cz/tech/unix/print.html>.
 
 
+## Tested Distributions
+
+| Distribution | Status  |
+|--------------|---------|
+| Ubuntu 20.04 | Working |
+| ArchLinux    | Working |
+
 ## Repository structure
 
 | File                     | Description                                      |