(SLV-366) Add docs for Large deployment

This commit adds a document for using the pe_xl module to deploy
a "PE Large Architecture".  An architecture diagram for the supported
deployment is included for clarity.  Currently, deploying the HA
version of the Large Architecture is not supported by the tooling.

Author: johnduarte

documentation/images/PE_Large_Architecture_no_HA.png

@@ -0,0 +1,67 @@
+# PE Large Architecture
+
+
+## Overview
+
+This module can also be used to deploy a Puppet Enterprise Large Architecture.
+Such an deployment differs from an Extra Large Architecture in that it does
+**not** include an external database.  PuppetDB is served from the master.
+
+**NOTE:** Currently, the module does not deploy a Large Architecture with HA.
+The currently supported deployment architecture is shown below.
+
+![Large Architecture without HA](images/PE_Large_Architecture_no_HA.png)
+
+
+## Instructions
+
+The process for deploying a PE Large Architecture is very similar to the
+[basic_usage](basic_usage.md) for deploying the XL Architecture.  These two
+differ only in the parameters supplied to the bolt plans.  Specifically, the
+`puppetdb_database_host`, `master_replica_host`, and
+`puppetdb_database_replica_host` parameters need to be omitted in order to
+deploy a PE Large Architecture.
+
+Ensuring that the parameters above are omitted from the `params.json` file,
+the [basic usage instructions](basic_usage.md#basic-usage-instructions) can be
+used to run the `pe_xl` plan in order to install and configure the deployment.
+
+Example nodes.yaml Bolt inventory file:
+
+```yaml
+---
+groups:
+  - name: pe_xl_nodes
+    config:
+      transport: ssh
+      ssh:
+        host-key-check: false
+        user: centos
+        run-as: root
+        tty: true
+    nodes:
+      - pe-xl-core-0.lab1.puppet.vm
+      - pe-xl-compiler-0.lab1.puppet.vm
+      - pe-xl-compiler-1.lab1.puppet.vm
+```
+
+Example params.json Bolt parameters file:
+
+```json
+{
+  "install": true,
+  "configure": true,
+  "upgrade": false,
+
+  "master_host": "pe-xl-core-0.lab1.puppet.vm",
+  "compiler_hosts": [
+    "pe-xl-compiler-0.lab1.puppet.vm",
+    "pe-xl-compiler-1.lab1.puppet.vm"
+  ],
+
+  "console_password": "puppetlabs",
+  "dns_alt_names": [ "puppet", "puppet.lab1.puppet.vm" ],
+  "compiler_pool_address": "puppet.lab1.puppet.vm",
+  "version": "2018.1.4"
+}
+```