docs: add missing syntax highlight (gatsbyjs#21722)

Naturalclar · LB · web-flow · commit 5b76f2550a7b · 2020-02-25T13:17:45.000-05:00
* docs: add missing syntax highlight

* docs: add title to json example

* Apply suggestions from code review

Co-Authored-By: LB &lt;laurie@gatsbyjs.com&gt;

Co-authored-by: LB &lt;laurie@gatsbyjs.com&gt;
diff --git a/docs/docs/using-graphql-playground.md b/docs/docs/using-graphql-playground.md
@@ -14,19 +14,19 @@ GraphQL Playground is a way for you to interact with the data your sources and p
 
 To access this experimental feature utilizing GraphQL Playground with Gatsby, add `GATSBY_GRAPHQL_IDE` to your `develop` script in your `package.json`, like this:
 
-```json
+```json:title=package.json
 "develop": "GATSBY_GRAPHQL_IDE=playground gatsby develop",
 ```
 
 If you are on **Windows** then you should use:
 
-```
+```json:title=package.json
 "develop": "cross-env GATSBY_GRAPHQL_IDE=playground gatsby develop",
 ```
 
 If you haven't installed **cross-env**, you can do it with:
 
-```
+```shell
 npm install --save-dev cross-env
 ```
 
