Add authored Age skies and celestial pages (#44)

README.md

@@ -124,6 +124,17 @@ the top or underside of one of its blocks. Insert a bound Linking or Descriptive
 Book to activate it; the book remains visible on the receptacle. A Linking Book aimed at its
 own dimension still opens a visual portal, but travel requires Intra Linking.
 
+Sky writing includes eight color pages and a Static Sky page. Multiple sky-color
+pages blend their colors, tinting the Age sky, book preview, and the fallback
+surface of portals linked there. Multiple celestial-color pages blend for the
+next written sun or moon. An Age may have no suns or moons at all;
+Static Sky animates the sky with television-like noise. Sun and Moon pages add
+independent bodies; preceding color, size, angle, period, phase, and direction
+pages configure the next body. The third and each subsequent sun add increasing
+instability. Newly generated page-free Ages also choose a deterministic sky,
+color, and celestial arrangement from their Age seed; older saved Ages retain
+their previous sky.
+
 Craft a Book Binder from three iron ingots and five planks. Put leather or an
 empty Notebook in the left cover slot. Enter a title, then place a Link Panel
 Page first in the horizontal page strip. Click a page in the strip with a