docs: i2c: summary: document use of inclusive language

We now have the updated I2C specs and our own Code of Conduct, so we
have all we need to switch over to the inclusive terminology. Define
them here.

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>