modify something in 'dsl_v2.rst'
modify something in 'dsl_v2.rst'

in 'std.ssh' action's parameters, I think
'username' is Required
in 'std.email' action's parameters ,I think
'subject' and 'body' are Optional

Change-Id: Ie40780db9049e734a0592b539c4c26d4f38799ba

StackStorm/mistral,openstack/mistral,StackStorm/mistral,openstack/mistral