[expr.ref] Delete extraneous "the".

Accidentally misapplied from P3293R3.

Author: tkoeppe

source/expressions.tex

@@ -4221,7 +4221,7 @@
 If \tcode{E2} is a \grammarterm{splice-expression},
 then let \tcode{T1} be the type of \tcode{E1}.
 \tcode{E2} shall designate either
-a member of the \tcode{T1} or
+a member of \tcode{T1} or
 a direct base class relationship $(\tcode{T1}, \tcode{B})$.
 
 \pnum