docs: add JS docs to the inputs/outputs

Previously those were in the GH's wiki, but that's a bad DX.

libs/gallery/src/lib/components/gallery/gallery.component.ts

@@ -37,48 +37,135 @@ import { ViewerComponent } from '../viewer/viewer.component';
   imports: [CommonModule, ThumbsComponent, ViewerComponent],
 })
 export class GalleryComponent {
+  /**
+   * Gallery items to display
+   */
   @Input() items: GalleryItem[];
+  /**
+   * Initially selected item, 0-based
+   */
   @Input() selectedIndex = 0;
+  /**
+   * Aria labels
+   */
   @Input() aria: Aria = defaultAria;
+  /**
+   * Show left and right icons to navigate between images in the viewer
+   */
   @Input() arrows = true;
+  /**
+   * Displayes item descriptions if any are present in `GalleryItem`
+   */
   @Input() descriptions = false;
+  /**
+   * Text to be shown when media loading failed
+   */
   @Input() errorText: string;
+  /**
+   * Allow mouse swipes
+   */
   @Input() mouseGestures = true;
+  /**
+   * Allow touch swipes
+   */
   @Input() touchGestures = true;
   /**
    * Controls whether items outside gallery's scrollport should overflow it. When clip == false,
    * items overflowing the gallery will be visible on both sides. Otherwise they will be hidden
    * with `overflow: hidden`.
    */
   @Input() clip = true;
+  /**
+   * Show item counter in the slider area
+   */
   @Input() counter = true;
   @Input() counterOrientation: VerticalOrientation = 'bottom';
-  @Input() visibleItems = 1;
-  @Input() moveByItems?: number;
+  /**
+   * Either makes images load eagerly or lazily. The lazy loading is managed by the browser itself.
+   */
   @Input() loading: Loading = 'lazy';
+  /**
+   * Turns on infinite looping for swiping and arrows navigation.
+   */
   @Input() loop = false;
+  /**
+   * The way an image or video should fill its container.
+   */
   @Input() objectFit: ObjectFit = 'cover';
+  /**
+   * Right to left mode
+   */
   @HostBinding('class.rtl')
   @Input()
   isRtl: boolean;
+  /**
+   * By how many items the slider shifts when user navigates with arrows.
+   */
+  @Input() moveByItems?: number;
+  /**
+   * How many items are visible in the scrollport.
+   */
+  @Input() visibleItems = 1;
+  /**
+   * Custom template for gallery items.
+   */
   @Input() itemTemplate: TemplateRef<ItemTemplateContext>;
+  /**
+   * Custom item template for media that failed to load
+   */
   @Input() errorTemplate: TemplateRef<any>;
+  /**
+   * Custom template for navigation arrows for the slider.
+   */
   @Input() arrowTemplate: TemplateRef<any>;
+  /**
+   * Custom template whose content appears in the gallery viewer.
+   */
   @Input() contentTemplate: TemplateRef<ContentTemplateContext>;
+  /**
+   * Show thumbnail list.
+   */
   @Input() thumbs = true;
+  /**
+   * Scroll thumbnails automatically as you navigate in image viewer.
+   */
   @Input() thumbsAutoScroll = true;
+  /**
+   * Where thumbnails will be placed in relation to slider.
+   */
   @Input() thumbsOrientation: Orientation = 'bottom';
+  /**
+   * Show arrows to navigate thumbnails.
+   */
   @Input() thumbsArrows = true;
+  /**
+   * By how far in pixels the thumbnails are scrolled when using arrows.
+   */
   @Input() thumbsArrowSlideByLength: number;
+  /**
+   * Smooth or instant navigation in thumbnails.
+   */
   @Input() thumbsScrollBehavior: ScrollBehavior = 'smooth';
+  /**
+   * Custom template for thumbnail items.
+   */
   @Input() thumbTemplate: TemplateRef<ThumbTemplateContext>;
+  /**
+   * Custom template for navigation arrows in thumbnail list.
+   */
   @Input() thumbsArrowTemplate: TemplateRef<never>;
+  /**
+   * Custom template for thumbnails that failed to load.
+   */
   @Input() thumbErrorTemplate: TemplateRef<never>;
 
   @Output() itemClick = new EventEmitter<GalleryItemEvent>();
   @Output() thumbClick = new EventEmitter<GalleryItemEvent>();
   @Output() thumbHover = new EventEmitter<GalleryItemEvent>();
   @Output() descriptionClick = new EventEmitter<Event>();
+  /**
+   * Triggers when item or group of items gets selected, ie. they get displayed in scrollport.
+   */
   @Output() selection = new EventEmitter<GalleryItem>();
 
   @ViewChild(ViewerComponent) _viewerRef: ViewerComponent;