Fixes in class declaration

Fix typo in syntax block.

Add that class name cannot be 'self', 'parent' or 'static'.
Actually, 'self' and 'parent' are not reserved keywords. They are valid as function names, even if probably not a good idea. The only place where they are invalid is as class names. But you are correct for 'static' : it is a reserved keyword.

In the chapter on keywords, we state that 'A keyword is a name-like sequence of characters that is reserved, and cannot be used as a name.'. So, I didn't repeat that in the chapter on class name.

So, we could write :
 
*name* must not be 'self' or 'parent'.