Patch 7 (#2297)

* Update custom-buttons.md

Set the 'updatemenu method' link directly to the method instead of the page header.

* Update custom-buttons.md

Bolded phrases and additional explanation in the "methods" section.

Author: SylwiaOliwia2

doc/python/custom-buttons.md

@@ -34,10 +34,10 @@ jupyter:
 ---
 
 #### Methods
-The [updatemenu method](https://plot.ly/python/reference/#layout-updatemenus-buttons-method) determines which [plotly.js function](https://plot.ly/javascript/plotlyjs-function-reference/) will be used to modify the chart. There are 4 possible methods:
-- `"restyle"`: modify data or data attributes
-- `"relayout"`: modify layout attributes
-- `"update"`: modify data **and** layout attributes
+The [updatemenu method](https://plot.ly/python/reference/#layout-updatemenus-items-updatemenu-buttons-items-button-method) determines which [plotly.js function](https://plot.ly/javascript/plotlyjs-function-reference/) will be used to modify the chart. There are 4 possible methods:
+- `"restyle"`: modify **data** or data attributes
+- `"relayout"`: modify **layout** attributes
+- `"update"`: modify **data and layout** attributes; combination of `"restyle"` and `"relayout"`
 - `"animate"`: start or pause an [animation](https://plot.ly/python/#animations))