add Documentation and bitcoin protip (donation) meta-tag

Author: ppachur

README.md

@@ -9,3 +9,7 @@ Open up a browser on your smart tv and point it to [https://isnogood.de/rcg/](ht
 # issues
 
 The all-time-high section is inaccurate. If you know a (free) API which serves all-time-highs with accurate dates, please tell me or make a PR.
+
+# license
+
+This project is released under the terms of the MIT license. See [LICENSE](LICENSE) for more information.

index.html

@@ -7,6 +7,7 @@
     <meta property="og:url" content="https://rollercoasterguy.github.io" />
     <meta property="og:title" content="Bitcoin Roller Coaster Guy" />
     <meta property="og:image" content="https://raw.githubusercontent.com/rollercoasterguy/rollercoasterguy.github.io/master/images/page_thumb.jpg" />
+    <meta name="microtip" content="1EQQ2nE8eUEqQwqbpDQh8xUTa3F9VPiWkk" data-currency="btc">
     <meta property="og:type" content="website" />
 
     <title>Bitcoin Roller Coaster Guy</title>