Merge pull request #989 from github/djj-clarify-requirements

Clarify OS requirements

Author: davidjarzebowski

docs/requirements.md

@@ -5,12 +5,13 @@ storage and must have network connectivity with the GitHub Enterprise Server app
 
 ## Backup host requirements
 
-Backup host software requirements are modest: Linux or other modern Unix operating
-system (Ubuntu is highly recommended) with [bash][1], [git][2], [OpenSSH][3] 5.6 or newer, [rsync][4] v2.6.4 or newer, and [jq][11] v1.5 or newer.
+Backup host software requirements are modest: Ubuntu Linux operating system with [bash][1], [git][2], [OpenSSH][3] 5.6 or newer, [rsync][4] v2.6.4 or newer, and [jq][11] v1.5 or newer.
 
-The parallel backup and restore feature will require [GNU awk][10] and [moreutils][9] to be installed.
+Ubuntu is the operating system we use to test `backup-utils` and it’s what we recommend you use too. You are welcome to use a different operating system, and we'll do our best to help you if you run into issues. But we can't guarantee that we'll be able to resolve issues that are specific to that operating system.
+
+Additionally, we encourage the use of [Docker](docker.md), as it ensures compatible versions of the aforementioned software are available to backup-utils.
 
-We encourage the use of [Docker](docker.md), as it ensures compatible versions of the aforementioned software are available to backup-utils.
+The parallel backup and restore feature will require [GNU awk][10] and [moreutils][9] to be installed.
 
 The backup host must be able to establish outbound network connections to the
 GitHub appliance over SSH. TCP port 122 is used to backup GitHub Enterprise Server.