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/Building-a-mech-tutorial.md

@@ -99,8 +99,9 @@ class CmdShoot(Command):
         # we have an argument, search for target
         target = caller.search(self.args.strip())
         if target:
-            message = "BOOM! The mech fires its gun at %s" % target.key
-            location.msg_contents(message)
+            location.msg_contents(
+                f"BOOM! The mech fires its gun at {target.key}"
+            )
 
 class CmdLaunch(Command):
     # make your own 'launch'-command here as an exercise!