Add javadoc to calendar endpoint

Signed-off-by: Cedric Willekens <c.s.willekens@student.tudelft.nl>

src/main/java/nl/tudelft/queue/controller/AdminController.java

@@ -92,6 +92,12 @@ public class AdminController {
 		return "admin/view";
 	}
 
+	/**
+	 * Get a calendar view with all the labs.
+	 *
+	 * @param  model The model to fill out for Thymeleaf template resolution.
+	 * @return       The Thymeleaf template to resolve.
+	 */
 	@GetMapping("/calendar")
 	public String getAdminCoursesPage(Model model) {
 		Period currPeriod = new Period().start(LocalDateTime.now().minusDays(1))