fix: added missing ModalHeader exports to index (react-bootstrap#6228)

* converted to rtl.

* .

* Update AccordionButtonSpec.tsx

minor bug fixed.

* Update AccordionButtonSpec.tsx

minor changes

* Create AccordionButtonSpec.tsx

minor changes

* Update AccordionButtonSpec.tsx

minor changes

* Convert to rtl.

* added some files.

* Removed ModalContext.

Author: VibhorJaiswal

src/index.tsx

@@ -112,9 +112,13 @@ export { default as Modal } from './Modal';
 export type { ModalProps } from './Modal';
 
 export { default as ModalBody } from './ModalBody';
+
 export { default as ModalDialog } from './ModalDialog';
 export type { ModalDialogProps } from './ModalDialog';
 
+export { default as ModalHeader } from './ModalHeader';
+export type { ModalHeaderProps } from './ModalHeader';
+
 export { default as ModalFooter } from './ModalFooter';
 export { default as ModalTitle } from './ModalTitle';
 export { default as Nav } from './Nav';