added the removal note for codebase attr in object element (mdn#40557)

* added the removal note for codebase attr in object element

* added in the HTML heading

* Update files/en-us/mozilla/firefox/releases/142/index.md

Co-authored-by: Dipika Bhattacharya <dipika@foss-community.org>

---------

Co-authored-by: Dipika Bhattacharya <dipika@foss-community.org>

Author: dletorey

files/en-us/mozilla/firefox/releases/142/index.md

@@ -18,11 +18,13 @@ Firefox 142 is the current [Beta version of Firefox](https://www.firefox.com/en-
 
 <!-- ### Developer Tools -->
 
-<!-- ### HTML -->
+### HTML
 
 <!-- No notable changes. -->
 
-<!-- #### Removals -->
+#### Removals
+
+- The {{HTMLElement('object')}} element no longer supports the deprecated `codebase` attribute. Use the [`data`](/en-US/docs/Web/HTML/Reference/Elements/object#data) attribute instead. (See [Firefox bug 1973900](https://bugzil.la/1973900) for more details.)
 
 <!-- ### CSS -->