Draft graphiql doc (#8599)

* Draft graphiql doc

* Update introducing-graphiql.md

Author: shannonbux

docs/docs/images/graphiql-docs.png

@@ -2,7 +2,37 @@
 title: Introducing GraphiQL
 ---
 
-This is a stub. Help our community expand it.
+## What's in this tutorial?
 
-Please use the [Gatsby Style Guide](/docs/gatsby-style-guide/) to ensure your
-pull request gets accepted.
+In this guide, you'll be learning to use something called Graph_i_QL, a tool that helps you structure GraphQL queries correctly.
+
+## What is Graph_i_QL?
+
+Graph_i_QL is the GraphQL integrated development environment (IDE). It's a powerful (and all-around awesome) tool
+you'll use often while building Gatsby websites.
+
+You can access it when your site's development server is running--normally at
+<http://localhost:8000/___graphql>.
+
+## Example of using Graph_i_QL
+
+When you have <http://localhost:8000/___graphql> open, it will look something like what this video shows. In the video below, watch someone poke around the built-in `Site` "type" and see what fields are available
+on it—including the `siteMetadata` object.
+
+<video controls="controls" autoplay="true" loop="true">
+  <source type="video/mp4" src="/www/static/graphiql-explore.mp4"></source>
+  <p>Your browser does not support the video element.</p>
+</video>
+
+## How to use Graph_i_QL
+
+When the development server is running for one of your Gatsby sites, open Graph_i_QL at <http://localhost:8000/___graphql> and play with your data! Press <kbd>Ctrl + Space</kbd> (or use <kbd>Shift + Space</kbd> as an alternate keyboard shortcut) to bring up the autocomplete window and <kbd>Ctrl + Enter</kbd> to run the GraphQL query.
+
+Make sure to check out the Graph_i_QL docs in the upper right-hand corner of the IDE. It's easy to miss them, but they're worth visiting!
+
+![A diagram pointing out where to find the GraphiQl docs](graphiql-docs.png)
+
+## Other resources
+
+- See [Tutorial Part 5: Source Plugins](/tutorial/part-five/) for a more complete example of using Graph_i_QL
+- See the [READme for Graph_i_QL](https://github.com/graphql/graphiql)