Added a warning about using the sort command in icontool.py (Lawnchai…

…rLauncher#2019)

At the moment, 4 contributors have encountered errors when sorting through icontool.py, as a result, they needed to fix appfilter.xml to remove duplicates or pass a style check.

I added a warning about the current state of the command so that people avoid unnecessary work.

docs/icontool_guide.md

@@ -62,6 +62,8 @@ Note that the SVG file's name is based on the `drawable` attribute of the first
 Some common utilities are described below.
 
 ### Sorting appfilter.xml
+> [!WARNING]  
+> At the moment, the sorting works with errors: duplicates and extra spaces are added. It is recommended not to use it.
 ```console
 python3 ./icontool.py sort
 ```