docs: rewrite README to match wrapper documentation standard

[sayalibhavsar]

The problem

The current README is a 2-line stub with no documentation of command-line options, workflow, dependencies, examples, or troubleshooting.

Expected Behaviour

README should provide comprehensive, source-code-accurate documentation following the team's standard format (autohpl-wrapper style), covering:

• All command-line options (numa_streams-specific and general_setup)
• Step-by-step workflow for both numa_streams_run and run_numa_stream scripts
• Per-OS dependencies (RHEL, Ubuntu, SLES, Amazon Linux)
• STREAM operations, metrics, cache sizing, thread scaling
• Usage examples, output files, return codes, troubleshooting
• Flagged missing features (no results_schema.py, no JSON output, no verify_results)

Actual Behaviour

README contains only a title and one-sentence description. No operational documentation exists.

Relates to JIRA: RPOPC-937