YSHOP2-673: Add guiding text on the recommended aspect ratio (#376)

## JIRA Ticket

[YSHOP2-673](https://youcanshop.atlassian.net/browse/YSHOP2-673)

## QA Steps

- [ ] `pnpm i`
- [ ] `pnpm dev`

## Note

Leave empty when you have nothing to say


[YSHOP2-673]:
https://youcanshop.atlassian.net/browse/YSHOP2-673?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ

sections/desktop-slider.liquid

@@ -269,7 +269,8 @@
         {
           "type": "image_picker",
           "id": "image",
-          "label": "Image"
+          "label": "Image",
+          "info": "To ensure your images look great and load quickly, use a size of \"1920px x 1080px\" (16:9 aspect ratio)."
         },
         {
           "type": "richtext",

sections/multi-column.liquid

@@ -145,7 +145,8 @@
         {
           "id": "image",
           "type": "image_picker",
-          "label": "Image"
+          "label": "Image",
+          "info": "To ensure your images look great and load quickly, use a size of \"43px x 43px\" (1:1 aspect ratio)."
         },
         {
           "id": "heading",