Welcome to your VS Code Extension

What's in the folder

This folder contains all of the files necessary for your extension
package.json - this is the manifest file in which you declare your language support and define the location of the grammar file that has been copied into you extension.
syntaxes/gql.tmLanguage.json - this is the Text mate grammar file that is used for tokenization
language-configuration.json - this the language configuration, defining the tokens that are used for comments and brackets.

Make sure the language configuration settings in language-configuration.json are accurate
press F5 to open a new window with your extension loaded
create a new file with a file name suffix matching your language
verify that syntax highlight works and that the language configuration settings are working

you can relaunch the extension from the debug toolbar after making changes to the files listed above
you can also reload (Ctrl+R or Cmd+R on Mac) the VS Code window with your extension to load your changes

To add features such as intellisense, hovers and validators check out the VS Code extenders documentation at https://code.visualstudio.com/docs

To start using your extension with Visual Studio Code copy it into the <user home>/.vscode/extensions folder and restart Code.
To share your extension with the world, read on https://code.visualstudio.com/docs about publishing an extension.