New Feature: Table Support has not yet been documented in the Formatting help page, as a result, many users across the SE network are still displaying tables with images, which are invisible to visually impaired users. To be considerate and kind to them, please edit the aboved linked help page so that users know how to typeset table.
On Meta.SE, we have a "Tables" tab, so that users might be aware of this new feature. However, on other sites like Math.SE, there's no such feature. As a result, adding information about the Markdown syntax for tables in this help page is the easiest option.
Meta.SE edit box has "Tables" option.
Math.SE edit box doesn't have "Tables" option.