added a favicon

favicon_io/about.txt

@@ -0,0 +1,6 @@
+This favicon was generated using the following graphics from Twitter Twemoji:
+
+- Graphics Title: 1f680.svg
+- Graphics Author: Copyright 2020 Twitter, Inc and other contributors (https://github.com/twitter/twemoji)
+- Graphics Source: https://github.com/twitter/twemoji/blob/master/assets/svg/1f680.svg
+- Graphics License: CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

favicon_io/site.webmanifest

@@ -0,0 +1 @@
+{"name":"","short_name":"","icons":[{"src":"/android-chrome-192x192.png","sizes":"192x192","type":"image/png"},{"src":"/android-chrome-512x512.png","sizes":"512x512","type":"image/png"}],"theme_color":"#ffffff","background_color":"#ffffff","display":"standalone"}