docs: add missing eslint-plugin-node plugin to eslint docs (#9600)
docs: add missing eslint-plugin-node plugin to eslint docs (#9600)

The eslint-plugin-node is required for the recommended eslintrc configuration, but it's not listed in the installation instructions. Without this change, running eslint results in the error `Failed to load plugin node: Cannot find module 'eslint-plugin-node'`.
ChristopherBiscardi/gatsby,0x80/gatsby,ChristopherBiscardi/gatsby,gatsbyjs/gatsby,0x80/gatsby,mingaldrichgan/gatsby,gatsbyjs/gatsby,0x80/gatsby,ChristopherBiscardi/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,mingaldrichgan/gatsby,ChristopherBiscardi/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,mingaldrichgan/gatsby