Fix code formatting in website (stdlib)

Author: julienvey

doc/ref/stdlib.html

@@ -1599,7 +1599,7 @@ <h3 id="sets">Sets</h3>
       <p>Sets are represented as ordered arrays without duplicates.</p>
       <p>
         Note that the <code>std.set*</code> functions rely on the uniqueness and ordering
-        on arrays passed to them to work. This can be guarenteed by using <code>std.set(arr)<code>.
+        on arrays passed to them to work. This can be guarenteed by using <code>std.set(arr)</code>.
         If that is not the case, the functions will quietly return non-meaningful results.
       </p>
       <p>