Update README.md

Adding info on how to use this via a proxy.

roles/manifest/README.md

@@ -48,3 +48,24 @@ Download the Subscription Manifest from the Red Hat Customer Portal to localhost
         foreman_rhsm_password: "$ecur3p4$$w0rd"
         foreman_manifest_uuid: "01234567-89ab-cdef-0123-456789abcdef"
 ```
+
+Download the Subscription Manifest from the Red Hat Customer Portal, via a proxy, to localhost before uploading to Foreman server:
+
+```yaml
+- hosts: localhost
+  roles:
+    - role: theforeman.foreman.manifest
+      environment:
+        https_proxy: "http://proxy.example.com:3128"
+        no_proxy: "foreman.example.com"
+      vars:
+        foreman_server_url: https://foreman.example.com
+        foreman_username: "admin"
+        foreman_password: "changeme"
+        foreman_organization: "Default Organization"
+        foreman_manifest_path: "~/manifest.zip"
+        foreman_manifest_download: true
+        foreman_rhsm_username: "happycustomer"
+        foreman_rhsm_password: "$ecur3p4$$w0rd"
+        foreman_manifest_uuid: "01234567-89ab-cdef-0123-456789abcdef"
+```