[DOCUMENTATION] Streamline User Guide

[IanHoang]

Is your feature request related to a problem? Please describe

Currently, OSB has a comprehensive User Guide section. We can streamline this to make it more digestible.

Describe the solution you'd like

Something like this might be beneficial. Open to other ideas as well.

opensearch-benchmark-documentation
├── quickstart
│   ├── run-osb
│   └── run-osb-with-your-cluster
├── user_guide
│   ├── concepts
│   │   └── target_throughput
│   ├── setup
│   │   ├── installation
│   │   └── configuration
│   ├── understanding_workloads
│   │   ├── anatomy_of_a_workload
│   │   ├── common_operations
│   │   └── choosing_a_workload
│   ├── running_workloads
│   │   └── running_distributed_workloads
│   ├── understanding_results
│   └── refine_benchmarking
│       ├── custom_workloads
│       │  ├── sharing_custom_workloads
│       │  ├── creating_custom_workloads
│       │  └── finetuning_custom_workloads
│       └── telemetry_devices
├── tutorials
│    └── sigv4_support
└─── references
    ├── metrics_reference
    │   ├── metric_records
    │   └── metric_keys
    ├── workload_reference
    │   ├── indices
    │   ├── test_procedures
    │   ├── operations
    │   └── corpora
    ├── command_reference
    │   ├── execute_test
    │   ├── command_flags
    │   ├── info
    │   ├── download
    │   ├── list
    │   └── compare
    └── telemetry_devices_reference

Describe alternatives you've considered

No response

Additional context

No response

[IanHoang]

Nate put out a PR here: opensearch-project/documentation-website#8387