Update copyright notice

lorensr · lorensr · commit 124abc66b38d · 2019-03-25T17:31:48.000-04:00
diff --git a/text/preface.md b/text/preface.md
@@ -20,4 +20,4 @@ We’ve found that building apps with GraphQL is less difficult and more fun, an
 
 ---
 
-*© 2018 The GraphQL Guide*
+*© 2019 The GraphQL Guide*

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`@@ -20,4 +20,4 @@ We’ve found that building apps with GraphQL is less difficult and more fun, an`
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`21`	`21`	`---`
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`23`		`-© 2018 The GraphQL Guide`
	`23`	`+© 2019 The GraphQL Guide`