README: textured moon disc and the enlarged sun/moon discs; note that the lunar map is inlined in the standalone build

README.md

@@ -24,7 +24,10 @@ dropped into an iframe or kiosk browser and left running.
   renders, plus terrain self-shadowing over the DEM height field.
 - **Realistic night sky**: ~8700 stars from the Yale Bright Star Catalogue
   (points sized by magnitude, coloured by temperature), rotated at the sidereal
-  rate for the site's latitude, a Milky Way band and a phase-correct moon.
+  rate for the site's latitude, a Milky Way band and a moon disc with a real
+  lunar surface map: the terminator comes from the sun direction, so crescent,
+  gibbous and full fall out of the geometry (sun and moon discs are drawn
+  enlarged - `CONFIG.sun`/`CONFIG.moon` - while the lighting stays physical).
 - **Aircraft**: low-poly jets (own CC0 mesh, generated by `tools/plane_gen.py`)
   on curved routes between real
   airfields, with a destination rolled at every take-off, sun-lit silhouettes
@@ -91,7 +94,8 @@ python3 build.py --check            # build to a temp file and verify, write not
 ```
 
 `--check` fails if anything is left that would need a sibling file (an external
-`<script src>` or a CSS `<link>`).
+`<script src>` or a CSS `<link>`), including the lunar surface map as a data
+URI, so the moon needs no sibling file either.
 
 Runtime *data* is fetched at load, but from public sources only: ESRI basemap
 tiles, the AWS elevation tiles and the Overpass mirrors are all CORS-enabled,