docs: create indexed table of applications and patterns with feature matrix

[kriscoleman]

docs: create indexed table of applications and patterns with feature matrix

As the repo grows, it becomes harder for vendors and customers to find the right example for their architecture. We should create an index document that maps each example to the Replicated features and deployment patterns it demonstrates.

Motivation

The Replicated advisory team uses this repository to find reference implementations for vendor engagements. Currently, finding the right example requires:

1. Reading every README manually
2. Inferring which features each example covers
3. Checking if the example is still current (SDK version, KOTS version, etc.)

An index would let us search by feature/pattern rather than by example name, dramatically reducing discovery time.

Acceptance Criteria

• Create at repo root with a feature matrix table
• Each row = one example (application or pattern)
• Each column = one feature/pattern dimension:
  • Delivery mode (KOTS / Helm CLI / EC v3 / air-gap)
  • Auto-update / continuous delivery (KOTS auto-deploy, GitHub Actions, Flux, ArgoCD)
  • Chart type (single chart / umbrella / multi-chart orchestration)
  • Stateful services (PostgreSQL, Redis, MinIO, OpenSearch, etc.)
  • Replicated features used (SDK, preflights, support bundles, snapshots, EP, custom metrics)
  • Security / compliance (air-gap, security contexts, NetworkPolicy, non-root)
  • Special requirements (GPU, CRDs, cert-manager, ingress, Dapr, KEDA, etc.)
  • SDK version (e.g., 1.12.1, 1.13.0)
  • Last verified date (so we know if an example is stale)
• Include a "Quick Find" section: "If you need X, look at Y"
  • e.g., "Multi-chart KOTS orchestration → MLflow"
  • e.g., "Embedded vs external database → MLflow"
  • e.g., "Support bundles in subcharts → wg-easy cert-manager wrapper"
  • e.g., "KOTS auto-update workflow → [example with auto-deploy config]"
• Add a CI check or scheduled workflow to validate that INDEX.md references existing examples (prevent drift)

Notes

This index would also be useful for:

• Replicated SEs during Proof-of-Value engagements
• Vendors who want to self-serve and find the right pattern without engaging support
• The advisory program to quickly match vendor needs to working examples

If an index feels too heavy, an alternative is YAML frontmatter in each example's README.md that gets compiled into the index by a script. This would keep the index in sync with the examples automatically.