[gnome-builder] doc: add docs on meson

[Christian Hergert <chergert src gnome org>]

commit 890d62a702c358b335cd29b636c93e1454ad87e6
Author: Christian Hergert <chergert redhat com>
Date:   Sat Jun 10 15:03:25 2017 -0700

    doc: add docs on meson

 doc/installation.rst |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
---
diff --git a/doc/installation.rst b/doc/installation.rst
index 11637ce..7a4fcf8 100644
--- a/doc/installation.rst
+++ b/doc/installation.rst
@@ -121,6 +121,13 @@ Keeping up with these requires updating much of the GNOME desktop.
 
 Please install via Flatpak, which does not have this restriction.
 
+We use Meson (and thereby Ninja) to build Builder.
+
+.. code-block:: sh
+
+   $ meson . build
+   $ ninja -C build install
+
 
 Troubleshooting
 ---------------