How do I add a description to a field in "GraphQL schema language" : <p>I have a graphql schema, a fragment of which looks like this:</p>

<pre><code>type User {
    username: String!
    password: String!
}
</code></pre>

<p>In graphiql, there is a description field, but it always says "self-descriptive". How do I add descriptions to the schema? </p>
