[doc] Update the coding style rule for API documentation
[doc] Update the coding style rule for API documentation

Signed-off-by: Douglas Reis <df95399f7253aef5711aa5e1f53e8824981313ab@lowrisc.org>

lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan