Match page ordering and content in `Sampler` section

[kaelynj]

Depends on #4614

└── Execute on QPUs V
    ├── ...
    ├── Sampler V
    │   ├── intro/hello world
    │   ├── inputs and outputs
    │   ├── options
    │   ├── e2e examples
    │   ├── BackendSampler → will move to the integrations sections 
    │   └── REST API
    ├── ...