Add missing type for `previewImagesInEditor`

types/easymde-test.ts

@@ -101,6 +101,7 @@ EasyMDE.toggleSideBySide(editor2);
 
 const editorImages = new EasyMDE({
     uploadImage: true,
+    previewImagesInEditor: false,
     imageAccept: 'image/png, image/bmp',
     imageCSRFToken: undefined,
     imageMaxSize: 10485760,

types/easymde.d.ts

@@ -181,6 +181,7 @@ declare namespace EasyMDE {
         parsingConfig?: ParsingOptions;
         placeholder?: string;
         previewClass?: string | ReadonlyArray<string>;
+        previewImagesInEditor?: boolean;
         previewRender?: (markdownPlaintext: string, previewElement: HTMLElement) => string;
         promptURLs?: boolean;
         renderingConfig?: RenderingOptions;