docs(material/dialog): add missing descriptions

Adds descriptions for public properties showing up in the
API docs.

DEPRECATED: `MatDialogClose#dialogRef` class member to become private.

Author: devversion

src/material/dialog/dialog-content-directives.ts

@@ -48,6 +48,11 @@ export class MatDialogClose implements OnInit, OnChanges {
   constructor(
     // The dialog title directive is always used in combination with a `MatDialogRef`.
     // tslint:disable-next-line: lightweight-tokens
+    /**
+     * Reference to the containing dialog.
+     * @deprecated `dialogRef` property to become private.
+     * @breaking-change 13.0.0
+     */
     @Optional() public dialogRef: MatDialogRef<any>,
     private _elementRef: ElementRef<HTMLElement>,
     private _dialog: MatDialog) {}
@@ -93,6 +98,7 @@ export class MatDialogClose implements OnInit, OnChanges {
   },
 })
 export class MatDialogTitle implements OnInit {
+  /** Unique id for the dialog title. If none is supplied, it will be auto-generated. */
   @Input() id: string = `mat-dialog-title-${dialogElementUid++}`;
 
   constructor(

src/material/dialog/dialog-ref.ts

@@ -54,6 +54,7 @@ export class MatDialogRef<T, R = any> {
   constructor(
     private _overlayRef: OverlayRef,
     public _containerInstance: _MatDialogContainerBase,
+    /** Id of the dialog. */
     readonly id: string = `mat-dialog-${uniqueId++}`) {
 
     // Pass the id along to the container.