docs(workflow): completes the list of conditions the merge action injects

[mergify-ci-bot]

The merge action page opens with the list of conditions Mergify adds to whatever
you wrote yourself, and two entries were off.

Merge protections were missing entirely. The engine builds the merge action's
minimum conditions from a shared helper that, when the Merge Protections product is
enabled on the repository, appends a requirement on the merge protections gate: a
check-run or a deployment, depending on
merge_protections_settings.reporting_method. Someone reading this list to work out
why a merge action is not firing would not have found the answer here.

The configuration-change entry said Mergify merges configuration changes "by
default", which reads as though a setting exists to turn that off. The setting that
used to do it is gone from the configuration schema, and the engine drops it from
configurations that still carry it. The behavior itself is unchanged, so the entry
now states it without implying a knob.

There is also a last entry for method: fast-forward, which injects
#commits-behind = 0 on top of the shared minimum conditions, and a note on what
the merge protections entry does not cover. A scheduled freeze decides the merge
protections check only when the merge queue is off; with the queue enabled, the
freeze is reported in that check but enforced by the queue, so the check can pass
while a freeze is running and the merge action goes ahead.

Evidence: the merge action's minimum conditions helper in the engine, which carries
no freeze condition of its own; the merge protections evaluator, which leaves freeze
rules out of the check conclusion when the merge queue product is enabled and keeps
them for reporting; and the configuration schema.

[mergify]

Merge Protections

🔴 2 of 5 protections blocking · waiting on 👀 reviews

	Protection	Waiting on
🔴	👀 Review Requirements	👀 reviews
🔴	🔎 Reviews	👀 reviews
🟢	Enforce conventional commit	—
🟢	📕 PR description	—
🟢	🚦 Auto-queue	—

🔴 👀 Review Requirements

Waiting for

• #approved-reviews-by >= 1

This rule is failing.

• any of:
  • #approved-reviews-by >= 1
  • author = dependabot[bot]
  • author = renovate[bot]
  • all of:
    • -head ~= ^docs-agent/
    • author = mergify-ci-bot

🔴 🔎 Reviews

Waiting for

• #review-requested = 0

This rule is failing.

• #review-requested = 0
• #changes-requested-reviews-by = 0
• #review-threads-unresolved = 0

---

Show 3 satisfied protections

🟢 Enforce conventional commit

Make sure that we follow https://www.conventionalcommits.org/en/v1.0.0/

• title ~= ^(fix|feat|internal|docs|style|refactor|perf|test|build|ci|chore|revert|ui)(?:\(.+\))?!?:

🟢 📕 PR description

• body ~= (?ms:.{48,})

🟢 🚦 Auto-queue

When all merge protections are satisfied, this pull request will be queued automatically.

Pull request has been modified.

[mergify-ci-bot]

🤖 I read this review, changed no file, and rewrote this pull request's title and description.