issue #2243 -- prefer f-strings over %-interpolation

edited docs to prefer f-strings, then str.format(), and remove %-interpolation

additional ad-hoc documentation fixes, as opportunities seen:
- replace Built-In Function (BIF) "min" variable with "mins"
- prefer BIF str(var) over "%s" % var
- reformat some code examples to clarify multiple args passed to functions
- change some single-quote strings to double-quotes for consistency
- fix mismatched parens

misc edits:
- add .vscode/ to gitignore

docs/source/Howto/Tutorial-Vehicles.md

@@ -293,7 +293,7 @@ class TrainObject(DefaultObject):
             roomref = self.db.rooms[idx]
             room = search_object(roomref)[0]
             self.move_to(room)
-            self.msg_contents("The train is moving forward to %s." % (room.name, ))
+            self.msg_contents(f"The train is moving forward to {room.name}.")
 ```
 
 We added a lot of code here. Since we changed the `at_object_creation` to add in variables we will