Update eslint-config package name. (vercel#8069)

### Description

Updating the name of the ESLint configuration package to use a
namespace, similar to our examples.

docs/pages/repo/docs/handbook/linting/eslint.mdx

@@ -1,5 +1,5 @@
 import { Tabs, Tab } from "../../../../../components/Tabs";
-import { Callout } from '../../../../../components/Callout'
+import { Callout } from "../../../../../components/Callout";
 
 # ESLint in a monorepo
 
@@ -22,21 +22,21 @@ apps
    ├─ package.json
    └─ .eslintrc.js
 packages
-└─ eslint-config-custom
+└─ eslint-config
    ├─ next.js
    ├─ library.js
    └─ package.json
 ```
 
-We've got a package called `eslint-config-custom`, and two applications, each with their own `.eslintrc.js`.
+We've got a package called `@repo/eslint-config`, and two applications, each with their own `.eslintrc.js`.
 
-### Our `eslint-config-custom` package
+### Our `@repo/eslint-config` package
 
-Our `eslint-config-custom` file contains two files, `next.js`, and `library.js`. These are two different ESLint configs, which we can use in different workspaces, depending on our needs.
+Our `@repo/eslint-config` file contains two files, `next.js`, and `library.js`. These are two different ESLint configs, which we can use in different workspaces, depending on our needs.
 
 Let's investigate the `next.js` lint configuration:
 
-```js filename="packages/eslint-config-custom/next.js"
+```js filename="packages/eslint-config/next.js"
 const { resolve } = require("node:path");
 
 const project = resolve(process.cwd(), "tsconfig.json");
@@ -87,9 +87,9 @@ It's a typical ESLint config that extends the [Vercel styleguide](https://github
 
 The `package.json` looks like this:
 
-```json filename="packages/eslint-config-custom/package.json"
+```json filename="packages/eslint-config/package.json"
 {
-  "name": "eslint-config-custom",
+  "name": "@repo/eslint-config",
   "license": "MIT",
   "version": "0.0.0",
   "private": true,
@@ -98,21 +98,20 @@ The `package.json` looks like this:
     "eslint-config-turbo": "^1.10.12"
   }
 }
-
 ```
 
-Note that the ESLint dependencies are all listed here. This is useful - it means we don't need to re-specify the dependencies inside the apps which import `eslint-config-custom`.
+Note that the ESLint dependencies are all listed here. This is useful - it means we don't need to re-specify the dependencies inside the apps which import `@repo/eslint-config`.
 
-### How to use the `eslint-config-custom` package
+### How to use the `@repo/eslint-config` package
 
-In our `web` app, we first need to add `eslint-config-custom` as a dependency.
+In our `web` app, we first need to add `@repo/eslint-config` as a dependency.
 
 <Tabs items={['npm', 'yarn', 'pnpm']} storageKey="selected-pkg-manager">
   <Tab>
 ```jsonc filename="apps/web/package.json"
 {
   "dependencies": {
-    "eslint-config-custom": "*"
+    "@repo/eslint-config": "*"
   }
 }
 ```
@@ -121,7 +120,7 @@ In our `web` app, we first need to add `eslint-config-custom` as a dependency.
 ```jsonc filename="apps/web/package.json"
 {
   "dependencies": {
-    "eslint-config-custom": "*"
+    "@repo/eslint-config": "*"
   }
 }
 ```
@@ -130,7 +129,7 @@ In our `web` app, we first need to add `eslint-config-custom` as a dependency.
 ```jsonc filename="apps/web/package.json"
 {
   "dependencies": {
-    "eslint-config-custom": "workspace:*"
+    "@repo/eslint-config": "workspace:*"
   }
 }
 ```
@@ -142,15 +141,11 @@ We can then import the config like this:
 ```js filename="apps/web/.eslintrc.js"
 module.exports = {
   root: true,
-  extends: ["custom/next"],
+  extends: ["@repo/eslint-config/next.js"],
 };
 ```
 
-By adding `custom/next` to our `extends` array, we're telling ESLint to look for a package called `eslint-config-custom`, and reference the file `next.js`.
-
-<Callout type="info">
-  You can avoid specifying the file by setting the entrypoint for your package. For example, setting `main: 'next.js'` in the `package.json`, could be loaded as simply `extends: ["custom"]` in your `.eslintrc.js`.
-</Callout>
+By adding `@repo/eslint-config/next.js` to our `extends` array, we're telling ESLint to look for a package called `@repo/eslint-config`, and reference the file `next.js`.
 
 ### Summary