Update src/const_eval.md

Co-Authored-By: chriskrycho <hello@chriskrycho.com>

Author: Centril

src/const_eval.md

@@ -11,7 +11,7 @@ compile time. In [const contexts](#const-context), these are the only allowed
 expressions, and are always evaluated at compile time. In other places, such as
 [`let` statements](statements.html#let-statements), constant expressions are
 Errors such as out of bounds [array indexing] or [overflow] are compiler errors
-if the value must be evaluated at compile time (i.e. in const contexts);
+if the value must be evaluated at compile time (i.e. in const contexts).
 Otherwise, these behaviors are warnings, but will likely panic at run-time.
 
 The following expressions are constant expressions, so long as any operands are