fix: detect additional content after ALL-CONTRIBUTORS-LIST:END (#2103)

## PR Checklist

- [x] Addresses an existing open issue: fixes #2102
- [x] That issue was marked as [`status: accepting
prs`](https://github.com/JoshuaKGoldberg/create-typescript-app/issues?q=is%3Aopen+is%3Aissue+label%3A%22status%3A+accepting+prs%22)
- [x] Steps in
[CONTRIBUTING.md](https://github.com/JoshuaKGoldberg/create-typescript-app/blob/main/.github/CONTRIBUTING.md)
were taken

## Overview

🎁

Author: JoshuaKGoldberg

src/options/readReadmeAdditional.test.ts

@@ -35,16 +35,35 @@ After.
 		expect(result).toBe("After.");
 	});
 
-	it("returns all content after contributors when there is a comment template notice", async () => {
+	it("returns all content after contributors when there is a spellchecker comment template notice", async () => {
 		const getReadme = () =>
 			Promise.resolve(`# My Package
 
 Usage.
 
+<!-- ALL-CONTRIBUTORS-LIST:END -->
 <!-- spellchecker:enable -->
 
 After.
 
+<!-- You can remove this notice if you don't want it 🙂 no worries! -->
+`);
+
+		const result = await readReadmeAdditional(getReadme);
+
+		expect(result).toBe("After.");
+	});
+
+	it("returns all content after contributors when there is a contributors comment template notice", async () => {
+		const getReadme = () =>
+			Promise.resolve(`# My Package
+
+Usage.
+
+<!-- ALL-CONTRIBUTORS-LIST:END -->
+
+After.
+
 <!-- You can remove this notice if you don't want it 🙂 no worries! -->
 `);
 

src/options/readReadmeAdditional.ts

@@ -1,4 +1,6 @@
-const indicatorAfterContributors = /<!--\s*spellchecker:\s*enable\s*-->/;
+const indicatorAfterAllContributors = /<!--\s*ALL-CONTRIBUTORS-LIST:END\s*-->/;
+const indicatorAfterAllContributorsSpellCheck =
+	/<!--\s*spellchecker:\s*enable\s*-->/;
 
 const indicatorBeforeTemplatedBy =
 	/> .* This package was templated with |<!-- You can remove this notice/;
@@ -9,7 +11,9 @@ export async function readReadmeAdditional(getReadme: () => Promise<string>) {
 		return undefined;
 	}
 
-	const indexAfterContributors = indicatorAfterContributors.exec(readme);
+	const indexAfterContributors =
+		indicatorAfterAllContributorsSpellCheck.exec(readme) ??
+		indicatorAfterAllContributors.exec(readme);
 	if (!indexAfterContributors) {
 		return undefined;
 	}