Update readme and license

LICENSE

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 MIT License
 
-Copyright (c) 2018 Adé Mochtar
+Copyright (c) 2019 Adé Mochtar
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

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+# Advent of Code private leaderboard ranking extension
+
+Visualize the ranking over time of an [Advent of Code](https://www.adventofcode.com/) private leaderboard.
+
+See https://amochtar.github.io/aoc-ranking/ for an interactive example.
+
+![#Global Leaderboard Ranking](example/ranking.png "Private Leaderboard Ranking Example")
+
+
+## Installation
+
+* Firefox - https://addons.mozilla.org/en-US/firefox/addon/aoc-ranking/
+* Chrome - https://chrome.google.com/webstore/detail/advent-of-code-ranking/jbnlafikncgjjhdkmfhokcplgahebmjl
+
+
+## Building locally
+
+To build the extension locally, run `npm install && npm run build`. This will generate an exploded version of the extension in the `dist/` folder.
+
+Use [`web-ext run`](https://github.com/mozilla/web-ext) from the `dist/` folder to run it locally in Firefox, or `web-ext build` to create a package.