Shortcode for creating an image with attributes.
The text inside the shortcode will be a link to the image.
The text in the title attribute, between the quotes, will be the image's titile attribute.
The text in the alt attribute, between the quotes, will be the image's alt attribute.
The text in the description attribute, between the quotes, will be the image's description attribute.
It's worth remembering that not all themes support description.