docs(rhoso-apps): expand readme for vault secret zero

[cjeanner]

Add a TOC, reorganize sections, and document the out-of-Git bootstrap credential (secret zero) for Vault or ESO on OpenShift. Clarify openstack-secrets defaults, wrap prose for readability, use reference-style links where helpful, and pin the in-repo VSO example URL to v0.2.0.

AI-Assist: Cursor; model=Composer-2; mode=agent; origin=cursor

[pinikomarov]

Line 387 - Patch operation type:

• op: replace
  path: /spec/appRole/secretRef
  value: "your-vault-approle-secret-name"
  ❌ Problem: replace fails if /spec/appRole/secretRef doesn't already exist in the base manifest.

✅ Suggested change to add:

• op: add
  path: /spec/appRole/secretRef
  value: "your-vault-approle-secret-name"

[cjeanner]

Line 387 - Patch operation type:

* op: replace
  path: /spec/appRole/secretRef
  value: "your-vault-approle-secret-name"
  ❌ Problem: replace fails if /spec/appRole/secretRef doesn't already exist in the base manifest.

✅ Suggested change to add:

* op: add
  path: /spec/appRole/secretRef
  value: "your-vault-approle-secret-name"

Ah, interesting, the add operation is actually more an add or replace. While this is a "dumb" example not really made to copy-paste as-is, I'll update it, since it won't break anything.