Adds details about new non-blocking logging mode

This functionality was added in moby/moby#28762.
It allows a user to specify what to do in cases when a log message can't
be sent, block the container's stdio or drop messages.

Also removes an erronious entry about a `nats` log driver, which does
not exist.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>

engine/admin/logging/overview.md

@@ -123,6 +123,13 @@ This example starts an `alpine` container with the `none` log driver.
 $ docker run -it --log-driver none alpine ash
 ```
 
+### Options for all drivers
+| Option            | Description | Example value |
+|-------------------|-------------|---------------|
+| `mode`            | Sets the logging mode, accepted values are `blocking` (default), and `non-blocking`. When `non-blocking` is set, if the log buffer fills up, log messages will be lost. How messages are dropped is left undefined. | `--log-opt mode=non-blocking`
+| `max-buffer-size` | Applicable only when `mode` is set to `non-blocking`, this sets the maxmimum size of the log buffer. Once this size is reach, log messages will be dropped. | `--log-opt max-buffer-size 5m`
+
+
 ## `json-file`
 
 `json-file` is the default logging driver, and returns logging output in JSON