Replace comments with single README

The package code generated a lot of extra comments, which felt sub-optimal. Instead, I've included a README.md file in the polyfills folder with the message and removed all mention of it from the code.

package/govuk-esm/vendor/polyfills/Date/now.mjs

@@ -1,13 +1,5 @@
 // @ts-nocheck
 
-/**
- * NOTE
- * 
- * These polyfills were generated using polyfill.io, which was reported as compromised on 25th June 2024.
- * 
- * We generated this code well before the compromise, and it is free of malicious code.
- * However, we recommend checking any polyfills you have generated in a similar way.
- */
 (function (undefined) {
 
     // Detection from https://github.com/Financial-Times/polyfill-library/blob/v3.111.0/polyfills/Date/now/detect.js

package/govuk-esm/vendor/polyfills/Document.mjs

@@ -1,13 +1,4 @@
 // @ts-nocheck
-
-/**
- * NOTE
- * 
- * These polyfills were generated using polyfill.io, which was reported as compromised on 25th June 2024.
- * 
- * We generated this code well before the compromise, and it is free of malicious code.
- * However, we recommend checking any polyfills you have generated in a similar way.
- */
 (function (undefined) {
 
 // Detection from https://github.com/Financial-Times/polyfill-service/blob/master/packages/polyfill-library/polyfills/Document/detect.js

package/govuk-esm/vendor/polyfills/Element.mjs

@@ -2,14 +2,6 @@ import './Document.mjs';
 
 // @ts-nocheck
 
-/**
- * NOTE
- * 
- * These polyfills were generated using polyfill.io, which was reported as compromised on 25th June 2024.
- * 
- * We generated this code well before the compromise, and it is free of malicious code.
- * However, we recommend checking any polyfills you have generated in a similar way.
- */
 (function(undefined) {
 
 // Detection from https://github.com/Financial-Times/polyfill-service/blob/master/packages/polyfill-library/polyfills/Element/detect.js