Add sample default override in README.md

[thdoan]

I read that "you can override any of the default options from the configurations," but I am not sure how to go about doing this. It would be helpful if you can add an example of how to override a default (e.g., keepClosingSlash: true for html-minifier-terser) in README.md.

[thdoan]

After some experimentation, this is the way:

export default defineConfig({
  integrations: [
    compress({
      html: {
        keepClosingSlash: true,
      },
    })
  ],
});

[NikolaRHristov]

I haven't included them because the options might change and so I found a link to the original options might be more helpful.