[6.0] d023c39c0 add git

[Dridi Boukelmoune]

commit d023c39c0133cba35d95e545adcd37c872e4a4cd
Author: Nils Goroll <nils.goroll at uplex.de>
Date:   Tue Apr 24 12:06:04 2018 +0200

    add git

diff --git a/doc/sphinx/installation/install.rst b/doc/sphinx/installation/install.rst
index 101db8ea0..896d29c65 100644
--- a/doc/sphinx/installation/install.rst
+++ b/doc/sphinx/installation/install.rst
@@ -100,6 +100,10 @@ Recommended, in particular if you plan on building custom vmods::
 
     sudo apt-get install autoconf-archive
 
+Optionally, to pull from a repository::
+
+    sudo apt-get install git
+
 Build dependencies on Red Hat / CentOS
 --------------------------------------
 
@@ -125,6 +129,10 @@ Optionally, to rebuild the svg files::
 
     yum install graphviz
 
+Optionally, to pull from a repository::
+
+    yum install git
+
 .. XXX autoconf-archive ? is this any helpful on the notoriously
    outdated Redhats?