Add Installation Overview information.

docs/Installation/Install-Binaries.md

@@ -6,6 +6,7 @@ description: Install Orion from binary distribution
 ## Prerequisites
 
 * [Java JDK](http://www.oracle.com/technetwork/java/javase/downloads/index.html)
+* [libsodium](Dependencies.md)
 
 !!!important
     Orion requires Java 8+ to compile; earlier versions are not supported.

docs/Installation/Overview.md

@@ -0,0 +1,13 @@
+title: Installation Overview
+description: Overview and requirements to install Orion
+<!--- END of page meta data -->
+
+# Installation Overview
+
+You can install Orion by:
+
+* [Installing the binary distribution](Install-Binaries.md) 
+* [Building from source](Build-From-Source.md)
+
+!!! important
+    Orion requires the [Sodium crypto library](Dependencies.md) (libsodium).

mkdocs.yml

@@ -53,6 +53,7 @@ theme:
   logo: orion_logo.svg
 nav:
   - Installation:
+    - Installation Overview: Installation/Overview.md
     - Dependencies: Installation/Dependencies.md
     - Install Binary Distribution: Installation/Install-Binaries.md
     - Build from Source: Installation/Build-From-Source.md