Add todo for removing components deprecated in v35.0.0.0 (#1957)

* add todo for removing components deprecated in v35.0.0.0

* prettier doesn't like punctuations at the end of the sentence!

Author: siddharthkp

src/deprecated/index.ts

@@ -6,6 +6,8 @@
  *  example: import {FormGroup} from '@primer/react/deprecated
  */
 
+// Deprecated in v35.0.0 on March 9, 2022
+// TODO: We can remove these 6 months after release: September 10, 2022
 export {default as BorderBox} from './BorderBox'
 export type {BorderBoxProps} from './BorderBox'
 export {default as ChoiceFieldset, Item} from './ChoiceFieldset'
@@ -69,3 +71,4 @@ export type {
   ButtonTableListProps,
   ButtonCloseProps
 } from './Button'
+// end of v35.0.0