doc: shell: update documentation to reflect bug fix #10207
doc: shell: update documentation to reflect bug fix #10207

Shell macro SHELL_DEFINE no longer needs new line character.
Specification has been updated accordingly.

Signed-off-by: Jakub Rzeszutko <db01fea5b4491dba4fc272e7096cf665c7b907b9@nordicsemi.no>

punitvara/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,punitvara/zephyr,punitvara/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,explora26/zephyr,GiulianoFranchetto/zephyr,nashif/zephyr,GiulianoFranchetto/zephyr,nashif/zephyr,finikorg/zephyr,ldts/zephyr,explora26/zephyr,nashif/zephyr,finikorg/zephyr,Vudentz/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,explora26/zephyr,ldts/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,explora26/zephyr,punitvara/zephyr,nashif/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,punitvara/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,finikorg/zephyr,Vudentz/zephyr,Vudentz/zephyr,ldts/zephyr,galak/zephyr,explora26/zephyr