Add example outputs

Author: Jamie Hannaford

docs/userguide/Clients.md

@@ -120,20 +120,28 @@ $client->setDefaultOption('headers/X-Custom-Header', 'FooBar');
 
 php-opencloud will send a default `User-Agent` header for every HTTP request, unless a custom value is provided by the end-user. The default header will be in this format:
 
-> OpenCloud/xxx cURL/yyy PHP/zzz
+> User-Agent: OpenCloud/xxx cURL/yyy PHP/zzz
 
 where `xxx` is the current version of the SDK, `yyy` is the current version of cURL, and `zzz` is the current PHP version. To override this default, you must run:
 
 ```php
 $client->setUserAgent('MyCustomUserAgent');
 ```
 
+which will result in:
+
+> User-Agent: MyCustomUserAgent
+
 If you want to set a _prefix_ for the user agent, but retain the default `User-Agent` as a suffix, you must run:
 
 ```php
 $client->setUserAgent('MyPrefix', true);
 ```
 
+which will result in:
+
+> User-Agent: MyPrefix OpenCloud/xxx cURL/yyy PHP/zzz
+
 where `$client` is an instance of `OpenCloud\OpenStack` or `OpenCloud\Rackspace`.
 
 ## 5. Other functionality