Docs: Supplying custom Output filename

[seangwright]

If I want to supply a custom output filename, I need to still supply output in the options, otherwise this library skips writing.

This is confusing!

const production = process.env.ELEVENTY_ENV === 'production';
const extension = production ? '.min' : '';

eleventyConfig.addPlugin(pluginESbuild, {
  entryPoints: {
    site: 'src/assets/scripts/site.js',
  },
  output: '_site/assets/scripts', // supply a value to trick plugin to execute, but overidden with 'outfile' below
  esbuild: {
    bundle: production,
    format: 'esm',
    minify: production,
    sourcemap: true,
    outfile: `_site/assets/scripts/site${extension}.js`,
  },
});

I realize that output is a nice convenience, but the way it interacts with outfile is unexpected.