feat: add addons.explanations to blockESLint (#1864)

## PR Checklist

- [x] Addresses an existing open issue: fixes #1849
- [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/next/blocks/blockESLint.test.ts

@@ -272,6 +272,7 @@ describe("blockESLint", () => {
 		const creation = testBlock(blockESLint, {
 			addons: {
 				beforeLint: "Before lint.",
+				explanations: ["This is a great config!", "You should use it!"],
 				extensions: [
 					"a.configs.recommended",
 					{
@@ -406,7 +407,13 @@ describe("blockESLint", () => {
 			    },
 			  ],
 			  "files": {
-			    "eslint.config.js": "import eslint from "@eslint/js";
+			    "eslint.config.js": "/*
+			This is a great config!
+			*/
+			/*
+			You should use it!
+			*/
+			import eslint from "@eslint/js";
 			import a from "eslint-plugin-markdown"
 			import b from "eslint-plugin-regexp"
 			import tseslint from "typescript-eslint";

src/next/blocks/blockESLint.ts

@@ -57,6 +57,7 @@ export const blockESLint = base.createBlock({
 	},
 	addons: {
 		beforeLint: z.string().optional(),
+		explanations: z.array(z.string()).default([]),
 		extensions: z.array(z.union([z.string(), zExtension])).default([]),
 		ignores: z.array(z.string()).default([]),
 		imports: z.array(zPackageImport).default([]),
@@ -74,7 +75,8 @@ export const blockESLint = base.createBlock({
 		};
 	},
 	produce({ addons, options }) {
-		const { extensions, ignores, imports, rules, settings } = addons;
+		const { explanations, extensions, ignores, imports, rules, settings } =
+			addons;
 
 		const importLines = [
 			'import eslint from "@eslint/js";',
@@ -197,7 +199,7 @@ Each should be shown in VS Code, and can be run manually on the command-line:
 				}),
 			],
 			files: {
-				"eslint.config.js": `${importLines.join("\n")}
+				"eslint.config.js": `${explanations.map((explanation) => `/*\n${explanation}\n*/\n`).join("")}${importLines.join("\n")}
 
 export default tseslint.config(
 	{ ignores: [${ignoreLines.join(", ")}] },