docs: Remove 'specify property field type' part from new feature tutorial.

This commit removes the part which mentions specifying the property field
type in new feauture tutorial as it is no longer required to specify the
type.

docs/tutorials/new-feature-tutorial.md

@@ -540,26 +540,6 @@ in. For example in this case of `mandatory_topics` it will lie in
 better to discuss it in the [community](https://chat.zulip.org/)
 before implementing it.*
 
-When defining the property, you'll also need to specify the property
-field type (i.e. whether it's a `bool`, `integer` or `text`).
-
-``` diff
-
-// static/js/settings_org.js
-var org_settings = {
-    msg_editing: {
-        // ...
-    },
-    msg_feed: {
-        // ...
-+       mandatory_topics: {
-+           type: 'bool',
-+       },
-    },
-};
-
-```
-
 Note that some settings, like `realm_msg_edit_limit_setting`,
 require special treatment, because they don't match the common
 pattern.  We can't extract the property name and compare the value of