Create rooms as private by default

templates/room_manager/create_room.html

@@ -44,7 +44,7 @@
     {% when Some with (room) %}
     <input type="checkbox" name="private" id="private" {% if room.private %} checked {% endif %}/>
     {%- when None -%}
-    <input type="checkbox" name="private" id="private"/>
+    <input type="checkbox" name="private" id="private" checked/>
     {%- endmatch -%}
     <label for="private">Private room | {% call utils::hint_text("A private room will not be displayed on the index page unless you already have a YAML file uploaded to it. The link to the room will need to be shared to other participants manually.") %}</label>