chore: add package details to mix.exs file (#7)

## Checklist

<!--
For each bullet, ensure your pr meets the criteria and write a note
explaining how this PR relates. Mark them as complete as they are done.
All top-level checkboxes should be checked regardless of their relevance
to the pr with a note explaining whether they are relevant or not.
-->

- [X] Code conforms to the [Elixir
Styleguide](https://github.com/christopheradams/elixir_style_guide)

## Problem

This is required for common-config-elixir to add package release stuff

## Details

I did not set the org, so this package will be public. We should include
a license as well @doomspork

mix.exs

@@ -10,7 +10,8 @@ defmodule Lunar.MixProject do
       elixirc_paths: elixirc_paths(Mix.env()),
       start_permanent: Mix.env() == :prod,
       version: "0.1.0",
-      test_coverage: [tool: ExCoveralls]
+      test_coverage: [tool: ExCoveralls],
+      package: package()
     ]
   end
 
@@ -37,4 +38,15 @@ defmodule Lunar.MixProject do
       {:excoveralls, "~> 0.17.1", only: :test}
     ]
   end
+
+  defp package do
+    [
+      files: ~w(lib mix.exs .formatter.exs README.md CHANGELOG.md),
+      licenses: ["UNLICENSED"],
+      links: %{
+        Changelog: "https://github.com/stordco/lunar/releases",
+        GitHub: "https://github.com/stordco/lunar"
+      }
+    ]
+  end
 end