Delete multiple box shadows release note (#2068)

Author: alice-i-cecile

release-content/0.16/release-notes/16502_Multiple_box_shadow_support.md

@@ -143,13 +143,6 @@ contributors = []
 prs = [17559]
 file_name = "17559_Basic_UI_text_shadows.md"
 
-[[release_notes]]
-title = "Multiple box shadow support"
-authors = ["@ickshonpe"]
-contributors = ["@alice-i-cecile"]
-prs = [16502]
-file_name = "16502_Multiple_box_shadow_support.md"
-
 [[release_notes]]
 title = "Add \"bevy_input_focus\" crate."
 authors = ["@viridia", "@alice-i-cecile"]