Updated new events in README.md. (#1670)

Author: kiatng

README.md

@@ -76,6 +76,8 @@ Most important changes will be listed here, all other changes since `19.4.0` can
 - `catalog/product_image/progressive_threshold`
 
 ### New Events
+- `adminhtml_block_widget_form_init_form_values_after`
+- `adminhtml_block_widget_tabs_html_before`
 - `adminhtml_sales_order_create_save_before`
 - `checkout_cart_product_add_before`
 - `sitemap_cms_pages_generating_before`