docs: updated contribution guidelines (#3760)

* docs: updated contribution guidelines

* fixed eslint errors

www/docs/sidebars.js

@@ -2,10 +2,9 @@
  * Custom sidebar definitions:
  * - To declare a sidebar element as part of the homepage sidebar, add className: 'homepage-sidebar-item'
  * - To add an icon:
- *   - add the icon in www/docs/src/theme/Icon/<IconName>/index.js as a React SVG element if it doesn't exist, where `<IconName>` is the camel case name of the icon
+ *   - add the icon in www/docs/src/theme/Icon/<IconName>/index.ts as a React SVG element if it doesn't exist, where `<IconName>` is the camel case name of the icon
  *   - add the mapping to the icon in www/docs/src/theme/Icon/index.js
  *   - add in customProps sidebar_icon: 'icon-name'
- * - To add a divider line, add in customProps sidebar_is_divider_line: true and set value/label to any value
  * - To add a group divider add in customProps sidebar_is_group_divider: true and set the label/value to the title that should appear in the divider.
  * - To add a back item, add in customProps:
  *   - sidebar_is_back_link: true