README: Add basic build directions

In particular, highlight the use of configure flags to control locating
X11 keyboard stuff when building for Wayland.

Of particular note, if the locale root is not specified, then xkbcommon
will look for them under $prefix (i.e. /usr/local/share/X11/locale).
But unless the user has specifically installed them there, it is better
to look in the standard system location, /usr/share/X11/locale.

Otherwise, xkbcommon will error when it can't find them, e.g.:

  xkbcommon: ERROR: ~/.XCompose:4:9: failed to expand %L to the locale Compose file
  xkbcommon: ERROR: ~/.XCompose:4:12: unterminated string literal

Signed-off-by: Bryce Harrington <bryce@osg.samsung.com>
Signed-off-by: Ran Benita <ran234@gmail.com>

README.md

@@ -9,6 +9,21 @@ and dead keys.
 
 See [Quick Guide](doc/quick-guide.md).
 
+## Building
+
+libxkbcommon is built the typical autoconf way:
+
+    ./autogen.sh
+    make
+
+To build for use with Wayland, you can disable X11 support while still
+using the X11 keyboard configuration resource files thusly:
+
+    ./autogen.sh --disable-x11 \
+        --with-xkb-config-root=/usr/share/X11/xkb \
+        --with-x-locale-root=/usr/share/X11/locale
+    make
+
 ## API
 
 While libxkbcommon's API is somewhat derived from the classic XKB API as found