chore: remove last vestiges of markdownlint

Author: JoshuaKGoldberg

.vscode/extensions.json

@@ -1,6 +1,5 @@
 {
 	"recommendations": [
-		"DavidAnson.vscode-markdownlint",
 		"dbaeumer.vscode-eslint",
 		"esbenp.prettier-vscode",
 		"streetsidesoftware.code-spell-checker"

README.md

@@ -25,7 +25,6 @@ pnpm dev
 <!-- spellchecker: disable -->
 <!-- ALL-CONTRIBUTORS-LIST:START - Do not remove or modify this section -->
 <!-- prettier-ignore-start -->
-<!-- markdownlint-disable -->
 <table>
   <tbody>
     <tr>
@@ -45,12 +44,9 @@ pnpm dev
   </tbody>
 </table>
 
-<!-- markdownlint-restore -->
 <!-- prettier-ignore-end -->
 
 <!-- ALL-CONTRIBUTORS-LIST:END -->
 <!-- spellchecker: enable -->
 
-<!-- You can remove this notice if you don't want it 🙂 no worries! -->
-
 > 💙 This package was templated with [`create-typescript-app`](https://github.com/JoshuaKGoldberg/create-typescript-app).