update logo images

public/images/logo-letter.svg

@@ -1,6 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 169 61">
-  <style>
-    @import url('https://fonts.googleapis.com/css?family=Lato');
-  </style>
-  <text font-family="Lato, sans-serif" font-size="48" x="0" y="48">GROWI</text>
-</svg>