Gemfile packages Solargraph language server for additional IntelliSense and code formatting capabilities with editors that support it.
Example configuration for Solargraph can be found in
.solargraph.yml.example file. Copy the contents of this file to
.solargraph.yml file for language server to pick this configuration up. Since
.solargraph.yml configuration file is ignored by Git, it's possible to adjust configuration according to your needs.
Refer to particular IDE plugin documentation on how to integrate it with Solargraph language server: