* feat: update doc for dispose return type

* Change return type to undefined

* Without prettier

* Revert prettier changes

* Add missing `dispose()` methods for AxesHelper and CameraHelper

* Add missing `dispose()` methods for Light and LightShadow

* Add `dispose()` to docs for AxesHelper and CameraHelper

* Add `dispose()` to docs for Lights and LightShadow

* Fix eslint issues

* Replace spaces with tabs in documentation

Fix reference to the webgl_shadowmap_performance example

Correct indent.

Seems it made sense to add the Extra Examples after the Code Example, but maybe that needs rethinking?

Embedded Single SpotLight iframe example into SpotLight.html doc

I changed to this description well "A point light that can cast a shadow in one direction with a falloff cone."
I put the examples at the top since they are most relevant.