Fixed grammar error. "tenminste" (instead of) -> "ten minste" (at minimum).

http://www.onzetaal.nl/taaladvies/advies/tenminste

src/Symfony/Bundle/FrameworkBundle/Resources/translations/validators.nl.xliff

@@ -24,7 +24,7 @@
             </trans-unit>
             <trans-unit id="6">
                 <source>You must select at least {{ limit }} choices</source>
-                <target>Selecteer tenminste {{ limit }} opties</target>
+                <target>Selecteer ten minste {{ limit }} opties</target>
             </trans-unit>
             <trans-unit id="7">
                 <source>You must select at most {{ limit }} choices</source>