Documenting the id

lib/squib/api/image.rb

@@ -34,6 +34,7 @@ module Squib
     #
     # @option opts range [Enumerable, :all] (:all) the range of cards over which this will be rendered. See {file:API.md#label-Specifying+Ranges Specifying Ranges}
     # @option opts file [String, Array] ('') file(s) to read in. If it's a single file, then it's use for every card in range. If the parameter is an Array of files, then each file is looked up for each card. If any of them are nil or '', nothing is done. See {file:API.md#Specifying+Files Specifying Files}
+    # @option opts id [String] (nil) if set, then only render the SVG element with the given id. Prefix '#' is optional. Note: the x-y coordinates are still relative to the SVG document's page
     # @option opts x [Integer] (0) the x-coordinate to place
     # @option opts y [Integer] (0) the y-coordinate to place
     # @option opts width [Integer] (:native) the pixel width that the image should scale to. SVG scaling is done with vectors, so the scaling should be smooth. When set to `:native`, uses the DPI and units of the loaded SVG document.