The gihub.ref description is confusing and incorrect, particularly for PRs

### Code of Conduct

- [x] I have read and agree to the GitHub Docs project's [Code of Conduct](https://github.com/github/docs/blob/main/.github/CODE_OF_CONDUCT.md)

### What article on docs.github.com is affected?

https://docs.github.com/en/actions/reference/workflows-and-actions/contexts#github-context

### What part(s) of the article would you like to see updated?

The description for `github.ref` is confusing, misleading and incorrect, particularly for PR events.

> The fully-formed ref of the branch or tag that triggered the workflow run. For workflows triggered by `push`, this is the branch or tag ref that was pushed. For workflows triggered by `pull_request` that were not merged, this is the pull request merge branch. If the pull request was merged, this is the head branch. For workflows triggered by `release`, this is the release tag created. For other triggers, this is the branch or tag ref that triggered the workflow run. This is only set if a branch or tag is available for the event type. The ref given is fully-formed, meaning that for branches the format is `refs/heads/`. For pull requests events except `pull_request_target` that were not merged, it is `refs/pull//merge`. `pull_request_target` events have the `ref` from the base branch. For tags it is `refs/tags/`. For example, `refs/heads/feature-branch-1`.

Firstly, it's quite hard to follow the different branching logic of that parapgrah. **Can this be formatted better**, e.g. with nested bullet points?

Secondly, particularly for PR events, the logic is quite unclear, and incorrect in some places. The description mentions

> pull requests events

but doesn't define them what these are. Is it the following subset of triggers?

- [`pull_request`](https://docs.github.com/en/actions/reference/workflows-and-actions/events-that-trigger-workflows#pull_request)
- [`issue_comment`](https://docs.github.com/en/actions/reference/workflows-and-actions/events-that-trigger-workflows#pull_request_comment-use-issue_comment)
- [`pull_request_review`](https://docs.github.com/en/actions/reference/workflows-and-actions/events-that-trigger-workflows#pull_request_review)
- [`pull_request_review_comment`](https://docs.github.com/en/actions/reference/workflows-and-actions/events-that-trigger-workflows#pull_request_review_comment)
- [`pull_request_target`](https://docs.github.com/en/actions/reference/workflows-and-actions/events-that-trigger-workflows#pull_request_target)

Assuming this is the case, my understanding of the logic is as follows:

1. `pull_request` events with a `closed` activity type that **were merged**: `github.ref` = `refs/heads/`
2. All other `pull_request` events: `github.ref` = `refs/pull//merge`
3. All `pull_request_target` events (potentially excluding merged events): `github.ref` = `refs/heads/`
4. `issue_comment`, `pull_request_review` and `pull_request_review_comment` (and potentially merged `pull_request_target`) events: `github.ref` = `refs/pull//merge`

Problems to highlight:

1. It's unclear whether "pull requests events except `pull_request_target` that were not merged" includes merged `pull_request_target` events. My tests suggest it doesn't; merged `pull_request_target` events show `refs/heads/main`, not `refs/pull//merge`. **What is this line trying to say?**
2. On a merged `pull_request` event, my tests show ``, not ``. **There is a mistake in the description.**
3. For `pull_request_target` events, regardless of PR direction (`main` -> `test` or `test` -> `main`), my tests show `refs/heads/main`. **Is it always the repo default, not the PR base?**
4. My tests show `issue_comment` events use `refs/heads/main` (regardless of PR direction), not `refs/pull//merge`. **Are these events not part of the PR logic? Does it always use the repo default?**
5. If we're being picky, there's a case to be made that "workflows triggered by `pull_request` that were not merged" means "`closed` and not merged" - meaning other activity types might not be included in the list. **This could be worded better**

Is the following summary more accurate?

- All `pull_request_target` events: `refs/heads/`
- Merged `pull_request` events: `refs/heads/`
- All other `pull_request` events, and all `pull_request_review` and `pull_request_review_comment` events: `refs/pull//merge`
- `issue_comment` events: `refs/heads/`

### Additional information

_No response_