doc: revise CI text in collaborator guide

Minor clarifications to text. For example, this moves the "(green or
yellow)" parenthetical closer to the text to which it applies. (It
applies only to Jenkins CI.)

doc/guides/collaborator-guide.md

@@ -209,11 +209,11 @@ the comment anyway to avoid any doubt.
 All fixes must have a test case which demonstrates the defect. The test should
 fail before the change, and pass after the change.
 
-Do not land any pull requests without a passing (green or yellow) CI run.
-A green GitHub Actions CI result is required. A passing
-[Jenkins CI](https://ci.nodejs.org/) is also required if PR contains changes
-that will affect the `node` binary. This is critical as GitHub Actions CI does
-not cover all the environments supported by Node.js.
+Do not land any pull requests without the necessary passing CI runs.
+A passing (green) GitHub Actions CI result is required. A passing (green or
+yellow) [Jenkins CI](https://ci.nodejs.org/) is also required if the pull
+request contains changes that will affect the `node` binary. This is because
+GitHub Actions CI does not cover all the environments supported by Node.js.
 
 <details>
 <summary>Changes that affect the `node` binary</summary>
@@ -294,7 +294,7 @@ in the form:
 To specify the branch this way, `refs/heads/BRANCH` is used
 (e.g. for `master` -> `refs/heads/master`).
 For pull requests, it will look like `refs/pull/PR_NUMBER/head`
-(e.g. for PR#42 -> `refs/pull/42/head`).
+(e.g. for pull request #42 -> `refs/pull/42/head`).
 * `REBASE_ONTO`: Change that to `origin/master` so the pull request gets rebased
 onto master. This can especially be important for pull requests that have been
 open a while.