FSA - Add User Request Framework to FSA SPA Documentation

[marija-ristin-msg]

Add a feature subpage to explain in short the User Request Framework, and then add a subpage to explain the final step needed for the FNOL configuration (The Backoffice part is previously explained on Help) with screenshots of the UI.

Draft content: https://wiki.msg-global.com/display/FSA/%28CXFSA-90%29+FNOL+Checkout+Creation+in+Backoffice#id-(CXFSA90)FNOLCheckoutCreationinBackoffice-[SPA]ConfigurableFNOLProcess