CB-13400: Added introduction to installation section (#809)
CB-13400: Added introduction to installation section (#809)

* added introduction to installation section

* implemented review comments

* implemented review comments

* implemented review comments

* implemented review comments

* implemented review comments

* implemented review comments

purplecabbage/cordova-docs,stevengill/cordova-docs,apache/cordova-docs,shazron/cordova-docs,stevengill/cordova-docs,purplecabbage/cordova-docs,shazron/cordova-docs,apache/cordova-docs,apache/cordova-docs,shazron/cordova-docs,stevengill/cordova-docs,shazron/cordova-docs,apache/cordova-docs,purplecabbage/cordova-docs,stevengill/cordova-docs,purplecabbage/cordova-docs