Double images fix

[tonilaukka]

There is a known issue with gatsby-plugin-mdx and gatsby-remark-issue which results in double images with the config described in the course. This can be fixed by adding gatsby-remark-images as plugin of gatsby-plugin-mxd.

    {
      resolve: 'gatsby-plugin-mdx',
      options: {
        defaultLayouts: {
          default: require.resolve('./src/components/layout.js'),
        },
        gatsbyRemarkPlugins: ['gatsby-remark-images'],
        plugins: ['gatsby-remark-images'],
      },
    },

[1Marc]

This was added as an annotation, but is now also added as a code snippet to the course errata.