doc: refine process.kill() and exit explanations
R: @sam-github, @nodejs/documentation
CC: @ronkorving
Ref: #2861
Fix: https://github.com/nodejs/node/issues/2924
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
R: @sam-github, @nodejs/documentation
CC: @ronkorving
Ref: #2861
Fix: https://github.com/nodejs/node/issues/2924