Fixed #3777 -- document an additional dependency (#3779)

diff --git a/docs/installation.rst b/docs/installation.rst
index 1aec914..e2ef1b6 100644
--- a/docs/installation.rst
+++ b/docs/installation.rst
@@ -114,7 +114,8 @@
 
 .. code-block:: console
 
-    $ sudo yum install gcc libffi-devel python-devel openssl-devel
+    $ sudo yum install redhat-rpm-config gcc libffi-devel python-devel \
+        openssl-devel
 
 
 Building