feat: add @ and ! to inline formatting

example.mharkup

@@ -96,6 +96,8 @@ here's a list of things the backtick can do:
 ` highlight a `_(special) element: ``_(special)
 ` add emphasis to `+(something): ``+(something)
 ` highlight something `*(important): ``*(important)
+` mark a non-word or name, like `@(mharkup): ``@(mharkup)
+` use monospace for `!(code): ``!(code)
 ` insert raw `{`text`}: `<`{`text`}>: `2{`<`{`text`}>}}: `2<`2{`<`{`text`}>}}>>: ...
 ` link `/here(somewhere): ``/here(somewhere)
 ` use an extension: ``\spec{...} or ``\spec<...>