Update plugin config and README accordingly

[soupette]

Signed-off-by: soupette cyril@strapi.io

Update the plugin configuration:

Before

collectionTypes: [
    {
      singularName: 'article',
      queryParams: {
        publicationState: 'preview',
        populate: {
          category: { populate: '*' },
          cover: '*',
          blocks: {
            populate: '*',
          },
        },
      },
    },
    {
      singularName: 'author',
    },
]

After

collectionTypes: [
    {
      singularName: 'article',
      queryParams: {
        publicationState: 'preview',
        populate: {
          category: { populate: '*' },
          cover: '*',
          blocks: {
            populate: '*',
          },
        },
      },
    },
   'author',
]