Adds support for hex, ex_doc, and Elixir

Elixir is a popular alternative on the BEAM, and by supporting those
users as part of the RAIK ecosystem, we can bring Riak to even more
projects.

To generate documents, run `rebar ex_doc`. This command builds
documentation and places it in a `doc` folder. Open `doc/index.html` to
view the generated documentation.

I have set up the framework so that we can publish this to hex and get
more exposure. The documentation should be pointed to hex instead of the
GitHub repo if we publish there.

Author: adkron

.gitignore

@@ -18,3 +18,4 @@ logs
 *.iml
 rebar3.crashdump
 *~
+doc/

README.md

@@ -54,7 +54,7 @@ ok
 ```
 
 With 8 nodes and 4 locations at your proposal, you can get a target n-val of 8 and a location nval of 4.
-That means that you can configure the system in such a way that you can loose 3 locations or 3 nodes and
+That means that you can configure the system in such a way that you can lose 3 locations or 3 nodes and
 still have one copy of all data available. Moreover, you have enough additional nodes to act take over the role of the lost nodes.
 
 ## Rebar3 plugin
@@ -81,3 +81,23 @@ Usage: rebar3 ring_calculator [-s <ring_size>] [-n <nodes>]
   -v, --verbose    print computation details
 ```
 
+## Elixir
+
+```elixir
+iex> Mix.install([{:ring_calculator, [github: "OpenRiak/ring_calculator", branch: "main"]}])
+iex> :ring_calculator.nvals(32, 8, 3)
+........................................x
+Best solution:
+Target Nval 8
+Location val 2
+Config [4,4]
+Ring: A1 B1 A2 B2 A3 B3 A4 B4 A1 B1 A2 B2 A3 B3 A4 B4 A1 B1 A2 B2 A3 B3 A4 B4 A1 B1 A2 B2 A3 B3 A4 B4 (0 violations)
+:ok
+```
+
+If you would like to be able to use `ring_calculator` from a mix project you can add the following
+dependency to your `mix.exs` deps.
+
+```elixir
+{:ring_calculator, github: "OpenRiak/ring_calculator", runtime: false}
+```

rebar.config

@@ -1,2 +1,10 @@
 {erl_opts, [debug_info]}.
-{deps, []}.
+{deps, []}.
+{plugins, [rebar3_hex, rebar3_ex_doc]}.
+{hex, [{doc, #{provider => ex_doc}}]}.
+{ex_doc, [
+    {source_url, <<"https://github.com/OpenRiak/ring_calculator">>},
+    {homepage_url, <<"https://github.com/OpenRiak/ring_calculator">>},
+    {extras, [<<"README.md">>, <<"LICENSE">>]},
+    {main, <<"README.md">>}
+]}.

src/ring_calculator.app.src

@@ -9,5 +9,7 @@
     {env, []},
     {modules, []},
     {licenses, ["Apache-2.0"]},
-    {links, []}
+    {links, [
+        {"GitHub", "https://github.com/OpenRiak/ring_calculator"}
+    ]}
  ]}.