If you want to use the same image tooltip as the homepage, you just need to add the 'image-tooltip' module and have a toolbar button with the class 'sc-image'. We didn't add it to the examples page editors for aesthetics (the tooltip is bigger than the editor) and thought it was sufficient to just demo the capability on the front page.
We realize and apologies for the lack of documentation for modules. One reason is the module interface is not finalized because we're not sure what the community will dream up and wanted to get feedback before making a decision that might unintentionally exclude certain use cases or encourage unsustainable designs. Depending on what's decided we will probably add functionality to the existing image tooltip. We'd love for you to be involved in the discussion if this is an area of interest.
We realize and apologies for the lack of documentation for modules. One reason is the module interface is not finalized because we're not sure what the community will dream up and wanted to get feedback before making a decision that might unintentionally exclude certain use cases or encourage unsustainable designs. Depending on what's decided we will probably add functionality to the existing image tooltip. We'd love for you to be involved in the discussion if this is an area of interest.