[shotwell] Update INSTALL for meson

[Jens Georg <jensgeorg src gnome org>]

commit 3ef15054eb17085dd618c1f1186ee86abb9a1daf
Author: Jens Georg <mail+gitkraken jensge org>
Date:   Sat Mar 31 23:07:39 2018 +0200

    Update INSTALL for meson

 INSTALL |    9 ++++-----
 1 files changed, 4 insertions(+), 5 deletions(-)
---
diff --git a/INSTALL b/INSTALL
index 3fd6efa..d9e22d2 100644
--- a/INSTALL
+++ b/INSTALL
@@ -4,13 +4,12 @@
 
     To build and install Shotwell, type the following commands:
 
-    $ [ -f configure ] || ./autogen.sh
-    $ ./configure
-    $ make
-    $ Optional: make install
+    $ meson build
+    $ ninja -C build
+    $ Optional: ninja -C build install
 
     * By default, Shotwell will install under /usr/local.  The configure script
-      can customize the prefix directory.  Run ./configure --help for
+      can customize the prefix directory.  Run meson build configure  for
       instructions and other installation options.
 
     * You may need to execute "make install" as root (i.e. sudo make install)