Very minor typo fix in functions.md
@@ -150,7 +150,7 @@ If a const function is called outside a [const context], it is indistinguishable
from any other function. You can freely do anything with a const function that
you can do with a regular function.
-Const functions have various restrictions to makes sure that they can't be
+Const functions have various restrictions to make sure that they can't be
evaluated at compile-time. It is, for example, not possible to write a random
number generator as a const function. Calling a const function at compile-time
will always yield the same result as calling it at runtime, even when called
