Restore JSS.tsx demo

Author: merceyz

docs/src/pages/system/basics/JSS.tsx

@@ -0,0 +1,20 @@
+import React from 'react';
+import { styled } from '@material-ui/styles';
+import { compose, spacing, palette } from '@material-ui/system';
+
+const Box = styled('div')(
+  compose(
+    spacing,
+    palette,
+  ),
+);
+
+function JSS() {
+  return (
+    <Box color="white" bgcolor="palevioletred" p={1}>
+      JSS
+    </Box>
+  );
+}
+
+export default JSS;