doc: update links for ErrorisError to point to MDN

Author: miguelmarcondesf

doc/api/deprecations.md

@@ -4045,7 +4045,7 @@ The [`util.types.isNativeError`][] API is deprecated. Please use [`Error.isError
 [`Buffer.isBuffer()`]: buffer.md#static-method-bufferisbufferobj
 [`Cipheriv`]: crypto.md#class-cipheriv
 [`Decipheriv`]: crypto.md#class-decipheriv
-[`Error.isError`]: https://github.com/tc39/proposal-is-error
+[`Error.isError`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error/isError
 [`REPLServer.clearBufferedCommand()`]: repl.md#replserverclearbufferedcommand
 [`ReadStream.open()`]: fs.md#class-fsreadstream
 [`Server.getConnections()`]: net.md#servergetconnectionscallback

doc/api/util.md

@@ -3719,7 +3719,7 @@ util.isArray({});
 [`'warning'`]: process.md#event-warning
 [`Array.isArray()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/isArray
 [`ArrayBuffer.isView()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer/isView
-[`Error.isError`]: https://github.com/tc39/proposal-is-error
+[`Error.isError`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error/isError
 [`JSON.stringify()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify
 [`MIMEparams`]: #class-utilmimeparams
 [`Object.assign()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign