Remove extra newlines at the beginning/end of files

Those are redundant, and yaml parser strips them in fact. By removing
them, loading and saving yaml file without any change indeed produce the
same output. This is useful for prepare_for_translation.py script (which
adds lang and ref tags) - to produce only change that indeed was made.

developer/debugging/vm-interface.md

@@ -11,7 +11,6 @@ ref: 47
 title: VM Configuration Interface
 ---
 
-
 Qubes VM have some settings set by dom0 based on VM settings. There are multiple configuration channels, which includes:
 
 - QubesDB