[FIX] - Zero to hero tutorials (#756)

* fix: #add-scaffold-pallet-structure step 2 snippets

* fix: build-custom-pallet snippets broken

* fix: pallet-unit-testing broken snippets

* fix: re-ordering zero-to-hero tutorials

* fix: snippets and frame-omni-bencher version

* fix: where to go next

Author: nhussein11