doc(browser-support) improved Firefox documentation (#4553)
doc(browser-support) improved Firefox documentation (#4553)

* docs(browser-support)

Added documentation on headless Firefox setup.

* docs(browser-support)

Documented Firefox-specific options.

angular/protractor,cnishina/protractor,mgiambalvo/protractor,cnishina/protractor,angular/protractor,mgiambalvo/protractor,angular/protractor,mgiambalvo/protractor,mgiambalvo/protractor,cnishina/protractor,cnishina/protractor,angular/protractor