README-linux.md: added libsndio-dev to the package list.

docs/README-linux.md

@@ -20,7 +20,7 @@ libtool libasound2-dev libpulse-dev libaudio-dev libx11-dev libxext-dev \
 libxrandr-dev libxcursor-dev libxi-dev libxinerama-dev libxxf86vm-dev \
 libxss-dev libgl1-mesa-dev libesd0-dev libdbus-1-dev libudev-dev \
 libgles1-mesa-dev libgles2-mesa-dev libegl1-mesa-dev libibus-1.0-dev \
-fcitx-libs-dev libsamplerate0-dev
+fcitx-libs-dev libsamplerate0-dev libsndio-dev
 
 Ubuntu 16.04 can also add "libwayland-dev libxkbcommon-dev wayland-protocols"
 to that command line for Wayland support.