Update explainer.md with cursor allowed values

Author: andypaicu

explainer.md

@@ -826,6 +826,7 @@ The following table details the list of CSS properties which should have special
 | `max-width`                | Will have a default value of 3 * 'fit-content'. If provided, the minimum computed value between the default and the provided values will be considered. However this does not apply if the element has a border with a width of at least 1px and a color that has a contrast ratio with the background-color of at least 3 and alpha of 1. |
 | `padding-top`              | Will only take effect if 'height' is set to 'auto'. In this case values over 1em will be corrected to 1em and `padding-bottom` will be set to the value of `padding-top`.                                                                                                                                                                  |
 | `padding-left`             | Will only take effect if 'width' is set to 'auto'. In this case values over 5em will be corrected to 5em and `padding-right` will be set to the value of `padding-left.`. This does not apply under the same border conditions as 'max-width', except 'padding-right' with still be set to the value of 'padding-left'.                 |
+| `cursor`                   | Will have a default value of 'pointer' but 'not-allowed' is also a valid value. Any other value (including custom images) is corrected to 'pointer'. |
 
 The following CSS properties are usable as normal: `font-kerning`, `font-optical-sizing`, `font-stretch`, `font-synthesis-weight`, 
 `font-synthesis-style`, `font-synthesis-small-caps`, `font-feature-settings`, `forced-color-adjust`, `text-rendering`, `align-self`, `anchor-name`