Remove unneeded | from AssignmentExpression
@@ -392,7 +392,7 @@ same trait object.
> **<sup>Syntax</sup>**\
> _AssignmentExpression_ :\
-> &nbsp;&nbsp; | [_Expression_] `=` [_Expression_]
+> &nbsp;&nbsp; [_Expression_] `=` [_Expression_]
An _assignment expression_ consists of a [place expression] followed by an
equals sign (`=`) and a [value expression]. Such an expression always has
