Add Changelog and update hex package metadata

Author: fhunleth

CHANGELOG.md

@@ -0,0 +1,5 @@
+# Changelog
+
+## v0.1.0
+
+Initial release

mix.exs

@@ -27,6 +27,25 @@ defmodule NervesTime.RTC.Abracon.MixProject do
     ]
   end
 
+  defp description do
+    "NervesTime.RTC implementation for Abracon Real-time Clocks"
+  end
+
+  defp package do
+    %{
+      files: [
+        "lib",
+        "test",
+        "mix.exs",
+        "README.md",
+        "LICENSE",
+        "CHANGELOG.md"
+      ],
+      licenses: ["Apache-2.0"],
+      links: %{"GitHub" => @source_url}
+    }
+  end
+
   defp deps do
     [
       {:circuits_i2c, "~> 0.3.6"},
@@ -36,15 +55,6 @@ defmodule NervesTime.RTC.Abracon.MixProject do
     ]
   end
 
-  def description, do: "NervesTime.RTC implementation for Abracon chips"
-
-  def package do
-    [
-      licenses: ["Apache-2.0"],
-      links: %{"GitHub" => @source_url}
-    ]
-  end
-
   def docs do
     [
       extras: ["README.md"],