message: TechDocsNotFound now uses ErrorPage from core with an optional docPath parameter
diff: */
  import React from 'react';
  -import { Typography, Button } from '@material-ui/core';
  -import { TechDocsPageWrapper } from './TechDocsPageWrapper';
  +import { ErrorPage } from '@backstage/core';
  export const TechDocsNotFound = () => {
  return (
  - <TechDocsPageWrapper
  - title="Documentation"
  - subtitle="Documentation available in Backstage"
  - >
  - <Typography>Error: Documentation not found</Typography>
  - <Typography>Path: {window.location.pathname}</Typography>
  - <Button color="primary" onClick={() => window.history.back()}>
  - Go back
  - </Button>
  - </TechDocsPageWrapper>
  + <div>
  + <ErrorPage
  + status="404"
  + statusMessage="Documentation not found"
  + docPath={window.location.pathname}
  + />
  + </div>
  );
  };
  