docs: fix links, add references, rename files (#5138)

docs/widgets/button.rst

@@ -1,27 +1,35 @@
+.. _lv_button:
+
+==================
 Button (lv_button)
-===============
+==================
 
 Overview
 ********
 
-Buttons have no new features compared to the `Base
-object </widgets/obj>`__. They are useful for semantic purposes and have
+Buttons have no new features compared to the :ref:`Base object <lv_obj>`__. They are useful for semantic purposes and have
 slightly different default settings.
 
 Buttons, by default, differ from Base object in the following ways: -
 Not scrollable - Added to the default group - Default height and width
 set to :cpp:enumerator:`LV_SIZE_CONTENT`
 
+.. _lv_button_parts_and_styles:
+
 Parts and Styles
 ****************
 
 -  :cpp:enumerator:`LV_PART_MAIN` The background of the button. Uses the typical
    background style properties.
 
+.. _lv_button_usage:
+
 Usage
 *****
 
-There are no new features compared to `Base object </widgets/obj>`__.
+There are no new features compared to :ref:`Base object <lv_obj>`.
+
+.. _lv_button_events:
 
 Events
 ******
@@ -32,6 +40,8 @@ Events
 
 Learn more about :ref:`events`.
 
+.. _lv_button_keys:
+
 Keys
 ****
 
@@ -39,14 +49,18 @@ Note that the state of :cpp:enumerator:`LV_KEY_ENTER` is translated to
 :cpp:enumerator:`LV_EVENT_PRESSED`, :cpp:enumerator:`LV_EVENT_PRESSING`
 and :cpp:enumerator:`LV_EVENT_RELEASED` etc.
 
-See the events of the `Base object </widgets/obj>`__ too.
+See the events of the :ref:`Base object <lv_obj>` too.
 
 Learn more about :ref:`indev_keys`.
 
+.. _lv_button_example:
+
 Example
 *******
 
 .. include:: ../examples/widgets/button/index.rst
 
+.. _lv_button_api:
+
 API
 ***