README.md: Mention about the Meson build support

...and also let people know how to use Meson to build lgi via Visual Studio in
an easier way in terms of finding the Lua or LuaJIT installation.

Remedies issue #290.

README.md

@@ -36,6 +36,27 @@ Alternatively, use make-based installation:
 
 Please note that on BSD-systems you may need to use 'gmake'.
 
+Building via Meson is also supported, with the same requirements, plus
+a Meson installation along with the Ninja build tool, in an empty build
+directory:
+
+    cd $(builddir)
+    meson $(lgi_srcroot) [--prefix=<prefix>] [--buildtype=<buildtype>] [--pkg-config-path=<pkgconfigpath>] [-Dlua-pc=...] [-Dlua-bin=...]
+    ninja
+	ninja test
+    [sudo] ninja install
+
+Building lgi with Visual Studio 2013 and later is also supported via
+Meson. It is recommended in this case that CMake is also installed to
+make finding Lua or LuaJIT easier, since Lua and LuaJIT support Visual
+Studio builds via batch files or manual compilation of sources. Ensure
+that `%INCLUDE%` includes the path to the Lua or LuaJIT headers, and
+`%LIB%` includes the path where the `lua5x.lib` from Lua or LuaJIT can be
+found, and ensure that `lua5x.dll` and `lua.exe` or `luajit.exe` can be
+found in `%PATH%` and run correctly. For building with LuaJIT, please do
+not pass in `-Dlua-pc=luajit`, but do pass in `-Dlua-bin=luajit` in the
+Meson command line so that the LuaJIT interpreter can be found correctly.
+
 ## Usage
 
 See examples in `samples/` directory.  Documentation is available in