docs: i2c: summary: document 'local' and 'remote' targets

Because Linux can be a target as well, add terminology to differentiate
between Linux being the target and Linux accessing targets.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Easwar Hariharan <eahariha@linux.microsoft.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Author: Wolfram Sang

Documentation/i2c/summary.rst

@@ -49,10 +49,15 @@ whole class of I2C adapters. Each specific adapter driver either depends on
 an algorithm driver in the ``drivers/i2c/algos/`` subdirectory, or includes
 its own implementation.
 
-A **target** chip is a node that responds to communications when addressed
-by the controller. In Linux it is called a **client**. Client drivers are kept
-in a directory specific to the feature they provide, for example
-``drivers/media/gpio/`` for GPIO expanders and ``drivers/media/i2c/`` for
+A **target** chip is a node that responds to communications when addressed by a
+controller. In the Linux kernel implementation it is called a **client**. While
+targets are usually separate external chips, Linux can also act as a target
+(needs hardware support) and respond to another controller on the bus. This is
+then called a **local target**. In contrast, an external chip is called a
+**remote target**.
+
+Target drivers are kept in a directory specific to the feature they provide,
+for example ``drivers/gpio/`` for GPIO expanders and ``drivers/media/i2c/`` for
 video-related chips.
 
 For the example configuration in figure, you will need a driver for your