Change heading prop back to old name

Author: sarah-j-lancaster

README.md

@@ -138,7 +138,7 @@ Enables external control of the expansion.
 
 Class(es) to apply to the 'heading' element.
 
-#### ariaLevel : `number` [*optional*, default: `3`]
+#### aria-level : `number` [*optional*, default: `3`]
 
 Will determine which 'heading' element is used in the markup. A value of `1`
 would make your element an `<h1>` tag, and likewise a value of `6` would make it
@@ -200,7 +200,7 @@ spec-compliant:
 -   Only ever use
     [phrasing content](https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/Content_categories#Phrasing_content)
     inside of your `AccordionItemHeading` component. If in doubt, use text only.
--   Remember to provide an `ariaLevel` prop to your `AccordionItemHeading`
+-   Remember to provide an `aria-level` prop to your `AccordionItemHeading`
     component, when you are nesting accordions. The levels are used by assistive
     technologies (eg. screenreaders) to infer structure, by default each heading
     uses `h3` .

src/components/AccordionItemHeading.spec.tsx

@@ -59,7 +59,7 @@ describe('AccordionItem', () => {
         });
     });
 
-    describe('ariaLevel prop', () => {
+    describe('aria-level prop', () => {
         it('is h3 by default', () => {
             const { getByTestId } = render(
                 <Accordion>
@@ -80,7 +80,7 @@ describe('AccordionItem', () => {
                     <AccordionItem>
                         <AccordionItemHeading
                             data-testid={UUIDS.FOO}
-                            ariaLevel={4}
+                            aria-level={4}
                         >
                             <AccordionItemButton />
                         </AccordionItemHeading>

src/components/AccordionItemHeading.tsx

@@ -5,7 +5,7 @@ import { assertValidHtmlId } from '../helpers/uuid';
 
 interface AccordianItemHeadingProps extends HeadingAttributes {
     className?: string;
-    ariaLevel?: number;
+    'aria-level'?: number;
 }
 
 export const SPEC_ERROR = `AccordionItemButton may contain only one child element, which must be an instance of AccordionItemButton.
@@ -19,7 +19,7 @@ From the WAI-ARIA spec (https://www.w3.org/TR/wai-aria-practices-1.1/#accordion)
 const Heading = React.forwardRef<HTMLHeadingElement, AccordianItemHeadingProps>(
     (
         {
-            ariaLevel = 3,
+            'aria-level': ariaLevel = 3,
             className = 'accordion__heading',
             ...props
         }: AccordianItemHeadingProps,