This is Pantheon's recommended starting point for forking new upstreams that work with the Platform's integrated Composer build process. Replace this with a description of your site. See upstream-config/README.md for advice on customizing this upstream and instructions on how to use it to create individual sites.
For more information and detailed installation guides, please visit the Integrated Composer Pantheon documentation: https://pantheon.io/docs/integrated-composer
This upstream uses roots/bedrock as a framework around the WordPress installation. You can head over there for more information about Bedrock and Composer for WordPress: https://roots.io/docs/bedrock/master/composer/