let config.file_watcher be the way to enable the evented file watcher

Before this commit, the sole presence of the Listen constant
enabled the evented file watcher (unless listen resorted to
the polling backend).

This way, applications may depend on listen for other stuff
independently of this feature. Also, allows teams with mixed
setups to decide at boot time whether the evented watcher
should be enabled for each particular instance.

1 files changed, 1 insertions, 1 deletions

diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index a286a7c5d2..ba2fb4c1cf 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -98,7 +98,7 @@ application. Accepts a valid week day symbol (e.g. `:monday`).
 
 * `config.exceptions_app` sets the exceptions application invoked by the ShowException middleware when an exception happens. Defaults to `ActionDispatch::PublicExceptions.new(Rails.public_path)`.
 
-* `config.file_watcher` the class used to detect file updates in the filesystem when `config.reload_classes_only_on_change` is true. Must conform to `ActiveSupport::FileUpdateChecker` API.
+* `config.file_watcher` is the class used to detect file updates in the file system when `config.reload_classes_only_on_change` is true. Rails ships with `ActiveSupport::FileUpdateChecker`, the default, and `ActiveSupport::EventedFileUpdateChecker` (this one depends on the [listen](https://github.com/guard/listen) gem). Custom classes must conform to the `ActiveSupport::FileUpdateChecker` API.
 
 * `config.filter_parameters` used for filtering out the parameters that
 you don't want shown in the logs, such as passwords or credit card