add Landing page (#7)

src/components/PageSpinner/PageSpinner.tsx

@@ -0,0 +1,16 @@
+import React, { FC } from 'react';
+import { Flex, Spinner } from '@chakra-ui/react';
+
+export const PageSpinner: FC = () => {
+  return (
+    <Flex w='full' h='100vh' justifyContent='center' alignItems='center'>
+      <Spinner
+        thickness='5px'
+        speed='0.65s'
+        emptyColor='gray.200'
+        color='green.500'
+        size='xl'
+      />
+    </Flex>
+  );
+};