Remove passive voice, add clarity (#1162)

lib/plug/builder.ex

@@ -21,21 +21,20 @@ defmodule Plug.Builder do
  end
  end
 
- Multiple plugs can be defined with the `plug/2` macro, forming a pipeline.
- The plugs in the pipeline will be executed in the order they've been added
- through the `plug/2` macro. In the example above, `Plug.Logger` will be
- called first and then the `:hello` function plug will be called on the
- resulting connection.
+ The `plug/2` macro forms a pipeline by defining multiple plugs. Each plug
+ in the pipeline is executed from top to bottom. In the example above, the
+ `Plug.Logger` module plug is called before the `:hello` function plug, so
+ the function plug will be called on the module plug's resulting connection.
 
- `Plug.Builder` also imports the `Plug.Conn` module, making functions like
- `send_resp/3` available.
+ `Plug.Builder` imports the `Plug.Conn` module so functions like `send_resp/3`
+ are available.
 
  ## Options
 
  When used, the following options are accepted by `Plug.Builder`:
 
  * `:init_mode` - the environment to initialize the plug's options, one of
- `:compile` or `:runtime`. Defaults `:compile`.
+ `:compile` or `:runtime`. The default value is `:compile`.
 
  * `:log_on_halt` - accepts the level to log whenever the request is halted
 
@@ -45,8 +44,8 @@ defmodule Plug.Builder do
 
  ## Plug behaviour
 
- Internally, `Plug.Builder` implements the `Plug` behaviour, which means both
- the `init/1` and `call/2` functions are defined.
+ `Plug.Builder` defines the `init/1` and `call/2` functions by implementing
+ the `Plug` behaviour.
 
  By implementing the Plug API, `Plug.Builder` guarantees this module is a plug
  and can be handed to a web server or used as part of another pipeline.
@@ -86,9 +85,9 @@ defmodule Plug.Builder do
 
  ## Halting a plug pipeline
 
- A plug pipeline can be halted with `Plug.Conn.halt/1`. The builder will
- prevent further plugs downstream from being invoked and return the current
- connection. In the following example, the `Plug.Logger` plug never gets
+ `Plug.Conn.halt/1` halts a plug pipeline. `Plug.Builder` prevents plugs
+ downstream from being invoked and returns the current connection.
+ In the following example, the `Plug.Logger` plug never gets
  called:
 
  defmodule PlugUsingHalt do