website: Remove h4 heading component and update document navigation

src/components/UI/docs/DocumentNav.tsx

@@ -16,7 +16,7 @@ export const DocumentNav: FC<Props> = ({ content }) => {
     .filter(item => item.startsWith('##'))
     .filter(item => !item.startsWith('####'))
     .map(item => parseHeadingId([item]))
-    .filter(item => item);
+    .filter(item => item)
 
   const activeHash = useActiveHash(parsedHeadings.map(heading => heading!.headingId));
 

src/components/UI/docs/MDComponents.tsx

@@ -91,13 +91,6 @@ const MDComponents = {
       </Heading>
     );
   },
-  h4: ({ children }: any) => {
-    return (
-      <Heading as='h4' mb='2.5 !important' {...h4} id={children}>
-        {children}
-      </Heading>
-    );
-  },
   // tables
   table: ({ children }: any) => (
     <Flex overflowX='auto'>