README: be a tiny bit more verbose

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

README

@@ -4,9 +4,15 @@ FFmpeg README
 1) Documentation
 ----------------
 
-* Read the documentation in the doc/ directory.
+* Read the documentation in the doc/ directory in git.
+  You can also view it online at http://ffmpeg.org/documentation.html
 
 2) Licensing
 ------------
 
 * See the LICENSE file.
+
+3) Build and Install
+--------------------
+
+* See the INSTALL file.