New page and assets to show the icon changing and selection UI (#113)

* link to new note-icons.md page

* assets for note-icons.md

* Create note-icons.md

Wiki/attributes.md

@@ -36,7 +36,7 @@ Labels are also searchable, enhancing note retrieval.
 - **`appCss`**: Marks CSS notes used to modify Trilium’s appearance
 - **`appTheme`**: Marks full CSS themes available in Trilium's options
 - **`cssClass`**: Adds a CSS class to the note's representation in the tree
-- **`iconClass`**: Adds a CSS class to the note's icon, useful for distinguishing notes visually
+- **`iconClass`**: Adds a CSS class to the note's icon, useful for distinguishing notes visually. See [note icons](note-icons.md)
 - **`pageSize`**: Specifies the number of items per page in note listings
 - **`customRequestHandler` and `customResourceProvider`**: Refer to [Custom request handler](custom-request-handler.md)
 - **`widget`**: Marks a note as a custom widget, added to Trilium's component tree

Wiki/note-icons.md

@@ -0,0 +1,7 @@
+# Note Icons
+
+Icons are useful for distinguishing notes. At the technical level, they are set by the **`iconClass`** attribute which adds a CSS class to the note. For example `#iconClass="bx bx-calendar"` will show a calendar instead of the default page or folder icon. Looking up and remembering the css class names is not necessary. While editing a note, click on the icon next to the title to bring up a chooser gallery:
+
+![change note icon](images/note-icon-change.png)
+
+![note icon gallery](images/note-icon-gallery.png)