Fixed typo in README for iOS.

docs/README-ios.md

@@ -64,7 +64,7 @@ Notes -- Retina / High-DPI and window sizes
 
 Window and display mode sizes in SDL are in "screen coordinates" (or "points",
 in Apple's terminology) rather than in pixels. On iOS this means that a window
-created on an iPhone 6 will have a size in screen cooordinates of 375 x 667,
+created on an iPhone 6 will have a size in screen coordinates of 375 x 667,
 rather than a size in pixels of 750 x 1334. All iOS apps are expected to
 size their content based on screen coordinates / points rather than pixels,
 as this allows different iOS devices to have different pixel densities