Fix doc-drift in contribution guide post Apr–May 2026 CI rewrite

[alex-frankel]

Why

The contribution guide (1-CONTRIBUTION-GUIDE/README.md) has drifted from what the workflows actually do, post Ould's Apr–May 2026 CI rewrite. New contributors following the doc verbatim will be told to type /verify (which does nothing — the workflow listens for /validate) and to expect a summarize-pr.yml workflow that doesn't exist. The Bicep section also tells contributors to omit azuredeploy.json from the PR, which produces broken "Deploy to Azure" buttons because customers click those button links directly to azuredeploy.json in master.

Surfaced while running #14752 as a canary for the new pipeline.

What changed

• /verify → /validate (7 occurrences in §2, the Contributor Workflow Summary, and the Diagnosing Failures section). The workflow source is the source of truth: ValidateSampleDeployments.yml matches startsWith(github.event.comment.body, '/validate').
• Drop §3 "Summarize PR (summarize-pr.yml)". That workflow doesn't exist. The AI summary is a job inside ValidateSampleDeployments.yml and fires automatically alongside /validate. Replaced with a one-line mention at the end of §2.
• "Three workflows" → "Two workflows" in the section opener. Matches the two workflows that actually drive the contributor PR flow (validate-samples.yml and ValidateSampleDeployments.yml). auto-fix.yml exists but is maintainer-only workflow_dispatch, not part of the contributor flow.
• Drop step 7 from the Contributor Workflow Summary (/summarize reference).
• Bicep section: change "must not be included in the PR as it will be built automatically when the sample is merged" to "should be included in the PR (compiled output of main.bicep)". The "Deploy to Azure" / "Visualize" buttons in each sample's README link directly to azuredeploy.json, so it must exist in the sample folder on master. Without it, the buttons 404 — which is exactly the breakage Update key-vault-create template to use RBAC instead of access policies #14704–Add key-vault-certificate-create template #14707 introduced and which @msmbaldwin's restore PRs (Add azuredeploy.json for key-vault-key-create #14739–Restore azuredeploy.json for key-vault-create #14742, merged today) just fixed.

Notes for @ouldsid

• The commit-generated-on-merge job in ValidateSampleDeployments.yml is the design path that would let contributors omit azuredeploy.json and have CI commit it for them. That's a great destination. Until commit-generated-on-merge writes azuredeploy.json to repo root, not the sample folder (path-stripping in upload-artifact@v4) #14754 (path-stripping bug) is fixed and the flow is reliable, the doc should describe what works today, which is "compile + commit it yourself." Once commit-generated-on-merge writes azuredeploy.json to repo root, not the sample folder (path-stripping in upload-artifact@v4) #14754 lands, this section can be updated again to mention the auto-gen path as a contributor option.
• This PR doesn't claim to be exhaustive on doc drift — there may be other doc files (sample-README.md, best-practices.md, the GH Actions wiki) that also need updating. Limited scope to the main contribution README.

cc @ouldsid