--save option no longer needed for npm > 5

As of npm 5.0.0, installed modules are added as a dependency by default, so the --save option is no longer needed.
Source: https://blog.npmjs.org/post/161081169345/v500

Author: avitorio

content/graphql/quick-start.md

@@ -9,7 +9,7 @@ In this chapter, we assume a basic understanding of GraphQL, and focus on how to
 Start by installing the required packages:
 
 ```bash
-$ npm i --save @nestjs/graphql graphql-tools graphql
+$ npm i @nestjs/graphql graphql-tools graphql
 ```
 
 Depending on what underlying platform you use (Express or Fastify), you must also install either `apollo-server-express` or `apollo-server-fastify`.