Adding Gatsby's graphql import

To avoid warnings during dev process.

src/pages/index.js

@@ -1,5 +1,5 @@
 import React from 'react'
-import { Link } from 'gatsby'
+import { Link, graphql } from 'gatsby'
 import get from 'lodash/get'
 import Helmet from 'react-helmet'
 
@@ -42,7 +42,7 @@ class BlogIndex extends React.Component {
 export default BlogIndex
 
 export const pageQuery = graphql`
-  query IndexQuery {
+  query {
     site {
       siteMetadata {
         title