wiki: Add missing Since annotations

docs/wiki/Configuration:-Window-Rules.md

@@ -419,6 +419,8 @@ window-rule {
 
 #### `open-maximized-to-edges`
 
+<sup>Since: next release</sup>
+
 Make the window open [maximized to edges](./Fullscreen-and-Maximize.md).
 
 ```kdl

docs/wiki/Fullscreen-and-Maximize.md

@@ -14,6 +14,8 @@ You can make a window open in a maximized column with the [`open-maximized true`
 
 ## Windows maximized to edges
 
+<sup>Since: next release</sup>
+
 You can maximize an individual window via `maximize-window-to-edges`.
 This is the same maximize as you can find on other desktop environments and operating systems: it expands a window to the edges of the available screen area.
 You will still see your bar, but not struts, gaps, or borders.