It depends how you do it.
If you do the command: /run versions.txt
it launches whichever program windows itself has associated with *.txt
If *.txt belongs to another program besides notepad, notepad has syntax which allows sending a file directly to it:
/run notepad.exe versions.txt
Whether your other program has command line syntax which allows directing files to it, but that's beyond the scope of this forum, and i assume other places have program-specific details like that