Documentation updated for options with --no prefix

[deepakpathania-zz]

• The current documentation states that multi-word options are camel-cased but doesn't clearly specify that the options with --no prefix negate the boolean value of the word that follows. This leads to a lot of confusion since the general intuition is to access it normally through program.noWord.
• Issues Why remove "--no" from option name? #700 and No way to know if parameter is set with --no- options #630 are due to this confusion only.
• This adds a small code sample in the main documentation clearing the confusion about the issue above.

[deepakpathania-zz]

Hey @vanesyan. Can you please review this? Thanks.

[roman-vanesyan]

@abetomo, you can merge commits yourself if you approve them, without asking me to approve too. 😄