README: extend dependecy list, link Windows compilation docs

Also, fix vo.rst, don't want to waste a separate commit on this.

DOCS/man/vo.rst

@@ -446,7 +446,7 @@ Available video output drivers are:
         RGB. If chroma is not subsampled, this option is ignored, and the
         luma scaler is used instead. Setting this option is often useless.
 
-    ``lscale-down=<filter>`
+    ``lscale-down=<filter>``
         Like ``lscale``, but apply these filters on downscaling
         instead. If these options are unset, the filter implied by ``lscale``
         will be applied.

README.md

@@ -42,16 +42,23 @@ Essential dependencies (incomplete list):
 
 - gcc or clang
 - X development headers (xlib, X extensions, libvdpau, libGL, libXv, ...)
-- Audio output development headers (libasound, pulseaudio)
-- FFmpeg libraries (libavutil libavcodec libavformat libswscale libavresample)
+- Audio output development headers (libasound/ALSA, pulseaudio)
+- FFmpeg libraries (libavutil libavcodec libavformat libswscale libavfilter
+  and either libswresample or libavresample)
   At least FFmpeg 2.1.4 or Libav 10 is required.
-- libjpeg (for screenshots)
-- Lua (strictly speaking optional, but required for the OSC pseudo-GUI)
+- libass
+- Lua (optional, required for the OSC pseudo-GUI)
+- libjpeg (optional, used for screenshots only)
+- Enca (optional, for subtitle charset detection)
+- vdpau and vaapi libraries for hardware decoding on Linux (optional)
 
 Libass dependencies:
 
 - gcc or clang, yasm on x86 and x86_64
 - fribidi, freetype, fontconfig development headers (for libass)
+- harfbuzz (optional, required for correct rendering of combining characters,
+  particularly for correct rendering of non-English text on OSX, and
+  Arabic/Indic scripts on any platform)
 
 FFmpeg dependencies:
 
@@ -72,6 +79,9 @@ If you are running Mac OSX and using homebrew we provide [homebrew-mpv][homebrew
 to date formula that compiles mpv with sensible dependencies and defaults for
 OSX.
 
+If you want to build a Windows binary, you either have to use MSYS2 and MinGW,
+or cross-compile from Linux with MinGW. See [Windows compilation][windows_compilation].
+
 FFmpeg vs. Libav
 ----------------
 
@@ -135,3 +145,4 @@ only if discretion is required.
 [mpv-devel]: https://groups.google.com/forum/?hl=en#!forum/mpv-devel
 [ffmpeg_vs_libav]: https://github.com/mpv-player/mpv/wiki/FFmpeg-versus-Libav
 [release-policy]: https://github.com/mpv-player/mpv/blob/master/DOCS/release-policy.md
+[windows_compilation]: https://github.com/mpv-player/mpv/blob/master/DOCS/compile-windows.md