feat(mix): update `mix` commands and descriptions (#10273)

plugins/mix/README.md

@@ -9,11 +9,11 @@ plugins=(... mix)
 ```
 ## Supported Task Types
 
-| Task Type               | Documentation                                            |
-|-------------------------|----------------------------------------------------------|
-| Elixir                  | [Elixir Lang](https://elixir-lang.org/)                  |
-| Phoenix v1.2.1 and below| [Phoenix](https://hexdocs.pm/phoenix/1.2.1/Phoenix.html) |
-| Phoenix v1.3.0 and above| [Phoenix](https://hexdocs.pm/phoenix/Phoenix.html)       |
-| Ecto                    | [Ecto](https://hexdocs.pm/ecto/Ecto.html)                |
-| Hex                     | [Hex](https://hex.pm/)                                   |
-| Nerves                  | [Nerves](https://nerves-project.org/)                    |
+| Task Type                | Documentation                                            |
+|--------------------------|----------------------------------------------------------|
+| Elixir                   | [Elixir Lang](https://elixir-lang.org/)                  |
+| Phoenix v1.2.1 and below | [Phoenix](https://hexdocs.pm/phoenix/1.2.1/Phoenix.html) |
+| Phoenix v1.3.0 and above | [Phoenix](https://hexdocs.pm/phoenix/Phoenix.html)       |
+| Ecto                     | [Ecto](https://hexdocs.pm/ecto/Ecto.html)                |
+| Hex                      | [Hex](https://hex.pm/)                                   |
+| Nerves                   | [Nerves](https://nerves-project.org/)                    |