Update object-literal.md

[kikorb]

The example was wrong. It stated that ?= is similar to JS || when the || will affect not only not defined scenario but also any falsy values (values that evaluate as false)

There are way too many differences between the 2:

1. window.var = false;
2. window.var = 0;
3. window.var = '';
4. window.var = null;

window.var ?= 'something' console.log(window.var) ->

1. false
2. 0
3. ''
4. 'something'

window.var ||= 'something' console.log(window.var) ->

1. 'something'
2. 'something'
3. 'something'
4. 'something'