Fixing typo

Fixing typo

source/adminguide/networking/security_groups.rst

@@ -41,7 +41,7 @@ desired set of rules.
 Any CloudStack user can set up any number of additional security groups.
 When a new instance is launched, it is assigned to the default security group
 unless another user-defined security group is specified. An instance can be a
-member of any number of security groups. You change the security groups of an instance only in a stopped state; you
+member of any number of security groups. You can change the security groups of an instance only in a stopped state; you
 can not move a running instance from one security group to another.
 
 You can modify a security group by deleting or adding any number of