User: update helptext to be clearer

 fixes xibosignage/xibo#3376

views/user-form-preferences.twig

@@ -52,7 +52,7 @@
                 {% endif %}
 
                 {% set title %}{% trans "Force current Library duration?" %}{% endset %}
-                {% set helpText %}{% trans "Assign all Media items based on their Library duration, and make it sticky so that changes in the library are not pulled into Layouts." %}{% endset %}
+                {% set helpText %}{% trans "Assign all Media items to Playlists based on their Library duration, and make it sticky so that changes in the library are not pulled into Layouts." %}{% endset %}
                 {{ forms.checkbox("useLibraryDuration", title, currentUser.getOptionValue("useLibraryDuration", 0), helpText) }}
 
                 {% set title %}{% trans "Auto show thumbnail column?" %}{% endset %}