Add missing "?" notion

Author: Discreater

src/items/type-aliases.md

@@ -3,7 +3,7 @@
 > **<sup>Syntax</sup>**\
 > _TypeAlias_ :\
 > &nbsp;&nbsp; `type` [IDENTIFIER]&nbsp;[_GenericParams_]<sup>?</sup>
->              [_WhereClause_]<sup>?</sup> ( `=` [_Type_] ) `;`
+>              [_WhereClause_]<sup>?</sup> ( `=` [_Type_] )<sup>?</sup> `;`
 
 A _type alias_ defines a new name for an existing [type]. Type aliases are
 declared with the keyword `type`. Every value has a single, specific type, but