Add what's new in 2.0.0 to the About popup

The layout test lets the changelog grow in height with its text, and still
checks its position and width.

popups/about_popup.gd

@@ -4,6 +4,19 @@ extends BasePopup
 
 ## What is new in each version, newest first.
 const WHATS_NEW: Dictionary = {
+	"2.0.0": "Reworked all popups, they dim the background and close when clicking outside
+	Fixed blurry text and the layout of the player list
+	Moved Sync to the top row and Settings next to the reset buttons
+	The inspiration and sync lists now show where each item starts
+	The sync result now looks right with any number of columns
+	Failed song downloads are now retried instead of getting stuck
+	The game no longer waits forever when the server does not answer
+	The song cache now fills up to the cache size in the settings
+	Statistics are turned back on when a new game starts
+	Fixed bugs with low winning scores and Show answer before a song is playing
+	The log now shows the time on every row
+	New app icon and a menu entry on Linux
+	Reorganized the code and added automated tests",
 	"1.9.0": "Made improvements to the Search window
 	Made small changes to the inspiration list scrolling
 	Made small changes to the player list