doc: Add vendor prefix for Kaohsiung

The 'koe' entry has been added to vendor-prefixes.txt to indicate
products from Kaohsiung Opto-Electronics Inc.
Signed-off-by: NLukasz Majewski <lukma@denx.de>
Signed-off-by: NRob Herring <robh@kernel.org>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -184,6 +184,7 @@ keymile	Keymile GmbH
 khadas	Khadas
 kinetic Kinetic Technologies
 kingnovel	Kingnovel Technology Co., Ltd.
+koe	Kaohsiung Opto-Electronics Inc.
 kosagi	Sutajio Ko-Usagi PTE Ltd.
 kyo	Kyocera Corporation
 lacie	LaCie