Make explicit reference to scrutinee expression in grammar snippet

Author: AloeareV

src/expressions/match-expr.md

@@ -2,11 +2,14 @@
 
 > **<sup>Syntax</sup>**\
 > _MatchExpression_ :\
-> &nbsp;&nbsp; `match` [_Expression_]<sub>_except struct expression_</sub> `{`\
+> &nbsp;&nbsp; `match` Scrutinee `{`\
 > &nbsp;&nbsp; &nbsp;&nbsp; [_InnerAttribute_]<sup>\*</sup>\
 > &nbsp;&nbsp; &nbsp;&nbsp; _MatchArms_<sup>?</sup>\
 > &nbsp;&nbsp; `}`
 >
+>_Scrutinee_ :\
+> &nbsp;&nbsp; [_Expression_]<sub>_except struct expression_</sub> 
+>
 > _MatchArms_ :\
 > &nbsp;&nbsp; ( _MatchArm_ `=>`
 >                             ( [_ExpressionWithoutBlock_][_Expression_] `,`