docs: add help links on github-bot rules (#3275)

Add help links for each automated github-bot rules.

<details><summary>Contributors' checklist...</summary>

- [x] Added new tests, or not needed, or not feasible
- [x] Provided an example (e.g. screenshot) to aid review or the PR is
self-explanatory
- [x] Updated the official documentation or not needed
- [x] No breaking changes were made, or a `BREAKING CHANGE: xxx` message
was included in the description
- [x] Added references to related issues and PRs
- [x] Provided any useful hints for running manual tests
</details>

contribs/github-bot/internal/check/comment.go

@@ -28,7 +28,7 @@ var (
 	// Regex for capturing only the checkboxes.
 	checkboxes = regexp.MustCompile(`(?m:^- \[[ x]\])`)
 	// Regex used to capture markdown links.
-	markdownLink = regexp.MustCompile(`\[(.*)\]\(.*\)`)
+	markdownLink = regexp.MustCompile(`\[(.*)\]\([^)]*\)`)
 )
 
 // These structures contain the necessary information to generate

contribs/github-bot/internal/config/config.go

@@ -27,12 +27,12 @@ type ManualCheck struct {
 func Config(gh *client.GitHub) ([]AutomaticCheck, []ManualCheck) {
 	auto := []AutomaticCheck{
 		{
-			Description: "Maintainers must be able to edit this pull request",
+			Description: "Maintainers must be able to edit this pull request ([more info](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/allowing-changes-to-a-pull-request-branch-created-from-a-fork))",
 			If:          c.Always(),
 			Then:        r.MaintainerCanModify(),
 		},
 		{
-			Description: "The pull request head branch must be up-to-date with its base",
+			Description: "The pull request head branch must be up-to-date with its base ([more info](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/keeping-your-pull-request-in-sync-with-the-base-branch))",
 			If:          c.Always(),
 			Then:        r.UpToDateWith(gh, r.PR_BASE),
 		},