Fix SSL configuration example in docs

Relates #610

docs/command_line_reference.rst

@@ -454,7 +454,7 @@ Client certificates can be presented regardless of the ``verify_certs`` setting,
 
 * Enable SSL, verify server certificates using public CA: ``--client-options="use_ssl:true,verify_certs:true"``. Note that you don't need to set ``ca_cert`` (which defines the path to the root certificates). Rally does this automatically for you.
 * Enable SSL, verify server certificates using private CA: ``--client-options="use_ssl:true,verify_certs:true,ca_certs:'/path/to/cacert.pem'"``
-* Enable SSL, verify server certificates using private CA, present client certificates: ``--client-options="use_ssl:true,verify_certs:true,ca_certs:'/path/to/cacert.pem',client_cert:'/path/to/client_cert.pem',client_key='/path/to/client_key.pem'"``
+* Enable SSL, verify server certificates using private CA, present client certificates: ``--client-options="use_ssl:true,verify_certs:true,ca_certs:'/path/to/cacert.pem',client_cert:'/path/to/client_cert.pem',client_key:'/path/to/client_key.pem'"``
 
 ``on-error``
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