docs: clarify README onboarding and integrations

[AnuradhaKaruppiah]

Overview

Polish the README refactor in NVIDIA#103 so new users see the
product purpose, supported harnesses, simplest working setup, common deployment
topologies, and integration paths in a clearer sequence.

This is a documentation-only change. It does not change runtime behavior or
public APIs.

Details

• Replace the hero diagram with the selected Applications/Evaluations/RL
  Rollouts version and update its alternative text.
• Reorganize the README around supported harnesses, a single-environment quick
  start, separate execution environments, execution flow, goal-based next
  steps, and roadmap items for custom harnesses and custom agents.
• Define consumer integrations as northbound and harness integrations as
  southbound across the README, documentation navigation, and consumer-skill
  index.
• Organize integration documentation under docs/integrations/consumer/ and
  docs/integrations/harness/, with a focused overview for each direction.
• Mirror that taxonomy for portable integration skills by moving the existing
  skill under skills/integrations/consumer/ and reserving
  skills/integrations/harness/ for the forthcoming adapter-authoring skill.
• Add missing integration pages for Hermes Agent and LangChain Deep Agents.

Validation

• git diff --check
• NODE_OPTIONS=--experimental-global-webcrypto npx --prefix docs --no-install fern check --warnings
  • Passed with zero errors. Redirect validation was skipped because no
    FERN_TOKEN was available.
• NODE_OPTIONS=--experimental-global-webcrypto npx --prefix docs --no-install fern docs broken-links --strict
  • Passed.
• Skill-bundle validation (quick_validate.py)
  • Passed for skills/integrations/consumer/nemo-fabric-integrate.

No runtime test suites were run because the change is documentation-only.

Where should the reviewer start?

Start with README.md for the revised onboarding flow and terminology, then
review docs/index.yml, docs/integrations/consumer/overview.mdx, and
docs/integrations/harness/overview.mdx for the matching integration
organization. Then review skills/README.md for the corresponding portable
skill layout.

Related Issues: (use one of the action keywords Closes / Fixes / Resolves / Relates to)

• Relates to docs: Reafactor the README.md NVIDIA/NeMo-Fabric#103

• I confirm this contribution is my own work, or I have the right to submit it under this project's license.

• I searched existing issues and open pull requests, and this does not duplicate existing work.