Support multiline graphql descriptions (Fix PrismJS#2405)

components.json

@@ -397,6 +397,7 @@
 		},
 		"graphql": {
 			"title": "GraphQL",
+			"optional": ["markdown"],
 			"owner": "Golmote"
 		},
 		"groovy": {

components/prism-graphql.js

@@ -1,5 +1,16 @@
 Prism.languages.graphql = {
 	'comment': /#.*/,
+	'multiline-string': {
+		pattern: /"""[\s\S]*?"""/,
+		greedy: true,
+		alias: 'string',
+		inside: {
+			'language-markdown': {
+				pattern: /[\s\S]+/,
+				inside: Prism.languages.markdown
+			}
+		}
+	},
 	'string': {
 		pattern: /"(?:\\.|[^\\"\r\n])*"/,
 		greedy: true

examples/prism-graphql.html

@@ -28,4 +28,19 @@ <h2>Keywords</h2>
   id
   name
   profilePic(size: 50)
-}</code></pre>
+}</code></pre>
+
+Markdown inside of descriptions require markdown to be loaded. On this page, checking Markdown before checking GraphQL should make the example below work properly.
+
+<h2>Descriptions</h2>
+<pre><code>"""
+This is a multiline description
+# Heading
+[Prism](http://www.prismjs.com)
+
+It can contain **Markdown
+	on multiple lines**
+"""
+
+"This is a single line description"
+</code></pre>