Update MIGRATION.md

[mcm1957]

npm uninstall eslint-plugin-security should be removed too

[foxriver76]

Never seen this plugin, I don't think it is very common. Before we add every edgy package, maybe we should leave a sentence to explain to uninstall all eslint plugins which are not afterwards added again to the new config. I mean someone could use this plugin again with the config if he wants to? It also works with flat config .. https://www.npmjs.com/package/eslint-plugin-security

[mcm1957]

OK, I agree that there could be some additional rule files.

I do not know where / when eslint-plugin-securita was invented but it was part of a discussion at Telegram and I no stubled at it when migrating srm adapter to community.

So I added an extra paragraph. Please read and feel free to adapt. I would like to guide those users who do not know what this plgin is good for to remiove it while ist comüpletly ok to leave / add ist for those who want to use these checks.

[foxriver76]

lgtm just a small "typo"

[mcm1957]

Thanks