Update docs/gettingstarted.md.

Fixez a typo in the 5th section of docs/gettingstarted.md and adds an alternative "structure" keyword for classes.

Signed-off-by: Username404-59 <w.iron.zombie@gmail.com>

docs/gettingstarted.md

@@ -87,7 +87,7 @@ int ** This is a compact comment, you can insert it pretty much anywhere ** a =
 ```
 
 ## 5 - Classes
-A class can be made with the keyword, their name, optional constructors (`~()`) where you can add parameters + code that will run when the class is instantiated, and the class body where you can define methods, properties etc:
+A class can be made with one of the `class` and `structure` keywords, its name, optional constructors (`~()`) where you can add parameters + code that will run when the class is instantiated, and the class body where you can define methods, properties etc:
 ```
 class Program {
   hello #= "Hello"