Make README.md compatible with latest format

Github changed the way it parses Markdown documents ruining the
formatting of the README in the process.

This change updates the README.md to keep it up to date with the latest
Markdown specification while adding the missing documentation for adding
extra parameters.

README.md

@@ -8,40 +8,40 @@ A [Postmark](https://postmarkapp.com/) Adapter for the [Bamboo](https://github.c
 
 The package can be installed as:
 
-  1. Add bamboo_postmark to your list of dependencies in `mix.exs`:
+1. Add bamboo_postmark to your list of dependencies in `mix.exs`:
 
-    ```elixir
-    def deps do
-      # Get from hex
-      [{:bamboo_postmark, "~> 0.2.0"}]
-      # Or use the latest from master
-      [{:bamboo_postmark, github: "pablo-co/bamboo_postmark"}]
-    end
-    ```
+```elixir
+def deps do
+  # Get from hex
+  [{:bamboo_postmark, "~> 0.2.0"}]
+  # Or use the latest from master
+  [{:bamboo_postmark, github: "pablo-co/bamboo_postmark"}]
+end
+```
 
-  2. Ensure bamboo is started before your application:
+2. Ensure bamboo is started before your application:
 
-    ```elixir
-    def application do
-      [applications: [:bamboo]]
-    end
-    ```
+```elixir
+def application do
+  [applications: [:bamboo]]
+end
+```
 
-  3. Add your Postmark API key to your config
+3. Add your Postmark API key to your config
 
-    > You can find this key as `Server API token` under the `Credentials` tab in each Postmark server.
+> You can find this key as `Server API token` under the `Credentials` tab in each Postmark server.
 
-    ```elixir
-    # In your configuration file:
-    #  * General configuration: config/config.exs
-    #  * Recommended production only: config/prod.exs
+```elixir
+# In your configuration file:
+#  * General configuration: config/config.exs
+#  * Recommended production only: config/prod.exs
 
-    config :my_app, MyApp.Mailer,
-          adapter: Bamboo.PostmarkAdapter
-          api_key: "my_api_key"
-    ```
+config :my_app, MyApp.Mailer,
+      adapter: Bamboo.PostmarkAdapter
+      api_key: "my_api_key"
+```
 
-  4. Follow Bamboo [Getting Started Guide](https://github.com/thoughtbot/bamboo#getting-started)
+4. Follow Bamboo [Getting Started Guide](https://github.com/thoughtbot/bamboo#getting-started)
 
 ## Using templates
 
@@ -90,3 +90,16 @@ defmodule MyApp.Mail do
   end
 end
 ```
+
+## Sending extra parameters
+
+You can send other extra parameters to Postmark such as TrackOpens or
+TrackLinks by using `put_params`.
+
+> See Postmark's API for a complete list of parameters supported.
+
+```elixir
+email
+|> put_params("TrackLinks", "HtmlAndText")
+|> put_params("TrackOpens", true)
+```

lib/bamboo/postmark_helper.ex

@@ -40,9 +40,8 @@ defmodule Bamboo.PostmarkHelper do
   Put extra message parameters that are used by Postmark. You can set things like TrackOpens or TrackLinks.
 
   ## Example
-    email
-    |> put_params(email, "TrackLinks", "HtmlAndText")
-    |> put_params(email, "TrackOpens", true)
+    put_params(email, "TrackLinks", "HtmlAndText")
+    put_params(email, "TrackOpens", true)
   """
   def put_param(%Email{private: %{message_params: _}} = email, key, value) do
     put_in(email.private[:message_params][key], value)