Rename misleading function dot_position to update_label in .add_updater() example (#4196)

Co-authored-by: Francisco Manríquez Novoa <[email protected]>

Author: irvanalhaq9

manim/mobject/mobject.py

@@ -1002,13 +1002,13 @@ def add_updater(
 
             class NextToUpdater(Scene):
                 def construct(self):
-                    def dot_position(mobject):
+                    def update_label(mobject):
                         mobject.set_value(dot.get_center()[0])
                         mobject.next_to(dot)
 
                     dot = Dot(RIGHT*3)
                     label = DecimalNumber()
-                    label.add_updater(dot_position)
+                    label.add_updater(update_label)
                     self.add(dot, label)
 
                     self.play(Rotating(dot, about_point=ORIGIN, angle=TAU, run_time=TAU, rate_func=linear))