Fix typo in REST Assured HTTP headers example

See gh-579

Author: 차지훈

docs/src/test/java/com/example/restassured/HttpHeaders.java

@@ -43,7 +43,7 @@ public void headers() throws Exception {
 									"Remaining requests permitted in current period"),
 							headerWithName("X-RateLimit-Reset").description(
 									"Time at which the rate limit period will reset"))))
-			.header("Authroization", "Basic dXNlcjpzZWNyZXQ=") // <4>
+			.header("Authorization", "Basic dXNlcjpzZWNyZXQ=") // <4>
 			.when().get("/people")
 			.then().assertThat().statusCode(is(200));
 		// end::headers[]