Improve UCA command parameter description

Hey @alexxcons,

I think the UCA command parameter description is a bit confusing and I wondered if we can make it better. Right now we have this:

%f the path to the first selected file or directory
%F the paths to all selected files and directories
%d directory containing the file that is passed in %f
%D directories containing the files that are passed in %F
%n the first selected filename (without path)
%N the selected filenames (without paths)

Here are my suggestions:

%n file name
%N file names
%d path
%D paths
%f path + file name
%F paths + file names

%n file name of the selected file
%N same as %n but for multiple files
%d path of the selected file
%D same as %d but for multiple files
%f path plus file name of the selected file
%F same as %f but for multiple files

%n file name of the selected file
%d path of the selected file
%f path plus file name of the selected file
Upper-case letters for the parameters will substitute to multiple paths/filenames for all selected files.

%n file name of the selected file
%N file names of all seleced files
%d path of the selected file
%D paths of all selected files
%f path plus file name of the selected file
%F paths plus file names of all seleted files

Personally I would go with the last suggestion. As you can see I also changed the order. We could also add this sentence to clarify things a bit more: "Note that files can also be directories.".

So what do you think?