add binding C q to welcome file (#145)

welcome.txt

@@ -7,6 +7,7 @@ To open multiple workspaces, run
 
 ved path/to/project1 path/to/project2
 
+If you never used vim before press `j` to move down
 
 Key bindings:
 
@@ -18,6 +19,7 @@ C r    reload current file
 C p    open ctrlp (fuzzy search)
 /      search in current file
 C g    copy current file's path to clipboard
+C q    exit the editor (type it twice in a row)
 t      go to the previous file
 gd     go to definition