Can't forward options to @storybook/addon-docs

[guillaumewuip]

@storybook/addon-docs accepts some options. One of the main use cases is passing a custom remark plugin to support tables in markdown files. This is referenced in the Storybook documentation directly:

addons: [
    {
      name: '@storybook/addon-docs',
      options: {
        mdxPluginOptions: {
          mdxCompileOptions: {
            remarkPlugins: [remarkGfm],
          },
        },
      },
    },
],

storybook-builder-rsbuild is implemented in a way that uses @storybook/addon-docs internally to leverage its webpack config. This prevents the mdxPluginOptions customization to work, as it never reach this hidden @storybook/addon-docs usage. Could we investigate how to pass this config from the user-land storybook config deep to the addon-docs present function?

Here is something that is working (tested locally):

1. in user-land, pass some builder options

   framework: {
     name: 'storybook-react-rsbuild',
     options: {
       docs: {
         mdxPluginOptions: {
           mdxCompileOptions: {
             remarkPlugins: [remarkGfm],
           },
         },
       },
     },
   }

2. patch storybook-builder-rsbuild to forward those options to addon-docs

   export default async (
     options: RsbuildBuilderOptions,
   ): Promise<RsbuildConfig> => {
   -  const appliedDocsWebpack = await docsWebpack({}, options)
   +  const appliedDocsWebpack = await docsWebpack({}, {  ...options, ...options.frameworkOptions.docs  })

Would you accept a pull request doing just that? I can propose it and also update the react-18 sandbox to show some remark-gfm support if needed.