Fixed typos in interface

cvat-canvas/README.md

@@ -108,7 +108,7 @@ Canvas itself handles:
         dragCanvas(enable: boolean): void;
         zoomCanvas(enable: boolean): void;
 
-        mode(): void;
+        mode(): Mode;
         cancel(): void;
         configure(configuration: Configuration): void;
     }

cvat-canvas/src/typescript/canvas.ts

@@ -54,7 +54,7 @@ interface Canvas {
     dragCanvas(enable: boolean): void;
     zoomCanvas(enable: boolean): void;
 
-    mode(): void;
+    mode(): Mode;
     cancel(): void;
     configure(configuration: Configuration): void;
 }