message: add system props and theme docs back
diff: @@ -5,6 +5,18 @@ import * as docs from '../components/docs'
  const SideNav = () => (
  <Relative>
  + <FlexContainer flexDirection="column" alignItems="start" p={5} borderBottom={1} borderColor="gray.2">
  + <NextLink href="/components/docs/system-props">
  + <Link nounderline scheme="gray-dark" href="/components/docs/system-props" m={0} mb={4}>
  + System Props
  + </Link>
  + </NextLink>
  + <NextLink href="/components/docs/primer-theme">
  + <Link nounderline scheme="gray-dark" href="/components/docs/primer-theme" m={0}>
  + Primer Theme
  + </Link>
  + </NextLink>
  + </FlexContainer>
  <Box width={248} bg="gray.0" display="inline-block">
  <Box pt={5} pl={5}>
  <Text fontWeight="bold" is="p" color="black" m={0} mb={3}>
  