Update README.md

* Mention rectangular blocks
* Mention directional modes

README.md

@@ -12,8 +12,8 @@ rav1e is an experimental AV1 video encoder. It is designed to eventually cover a
 
 * Intra and inter frames
 * 64x64 superblocks
-* 4x4 to 64x64 RDO-selected square blocks
-* DC, H, V, Paeth, and smooth prediction modes
+* 4x4 to 64x64 RDO-selected square and 2:1/1:2 rectangular blocks
+* DC, H, V, Paeth, smooth, and a subset of directional prediction modes
 * DCT, ADST and identity transforms (up to 64x64, 16x16 and 32x32 respectively)
 * 8-, 10- and 12-bit depth color
 * 4:2:0 (full support), 4:2:2 and 4:4:4 (limited) chroma sampling