docs: improve faq page

- add toc for faq page
- fix #79: add note about oem build
- add plat form specific instructions for qqmusic faq

src/components/HelpText/Headers.tsx

@@ -0,0 +1,42 @@
+import { Heading } from '@chakra-ui/react';
+import React from 'react';
+
+export interface HeaderProps {
+  children: React.ReactNode;
+  id?: string;
+  className?: string;
+}
+
+export function Header3({ children, className, id }: HeaderProps) {
+  return (
+    <Heading
+      as="h3"
+      id={id}
+      className={className}
+      pt={3}
+      pb={1}
+      borderBottom={'1px solid'}
+      borderColor="gray.300"
+      color="gray.800"
+      size="lg"
+    >
+      {children}
+    </Heading>
+  );
+}
+
+export function Header4({ children, className, id }: HeaderProps) {
+  return (
+    <Heading as="h4" id={id} className={className} pt={3} pb={1} color="gray.700" size="md">
+      {children}
+    </Heading>
+  );
+}
+
+export function Header5({ children, className, id }: HeaderProps) {
+  return (
+    <Heading as="h5" id={id} className={className} pt={3} pb={1} color="gray.700" size="sm">
+      {children}
+    </Heading>
+  );
+}