moving apidiff out of preview (#3595)

release-notes/3.0/api-diff/.Net/3.0.0_System.Security.md

@@ -0,0 +1,51 @@
+# System.Security
+
+``` diff
+ namespace System.Security {
++    public interface IStackWalk {
++        void Assert();
++        void Demand();
++        void Deny();
++        void PermitOnly();
++    }
++    public class PermissionSet : ICollection, IDeserializationCallback, IEnumerable, ISecurityEncodable, IStackWalk {
++        public PermissionSet(PermissionState state);
++        public PermissionSet(PermissionSet permSet);
++        public virtual int Count { get; }
++        public virtual bool IsReadOnly { get; }
++        public virtual bool IsSynchronized { get; }
++        public virtual object SyncRoot { get; }
++        public IPermission AddPermission(IPermission perm);
++        protected virtual IPermission AddPermissionImpl(IPermission perm);
++        public void Assert();
++        public bool ContainsNonCodeAccessPermissions();
++        public static byte[] ConvertPermissionSet(string inFormat, byte[] inData, string outFormat);
++        public virtual PermissionSet Copy();
++        public virtual void CopyTo(Array array, int index);
++        public void Demand();
++        public void Deny();
++        public override bool Equals(object o);
++        public virtual void FromXml(SecurityElement et);
++        public IEnumerator GetEnumerator();
++        protected virtual IEnumerator GetEnumeratorImpl();
++        public override int GetHashCode();
++        public IPermission GetPermission(Type permClass);
++        protected virtual IPermission GetPermissionImpl(Type permClass);
++        public PermissionSet Intersect(PermissionSet other);
++        public bool IsEmpty();
++        public bool IsSubsetOf(PermissionSet target);
++        public bool IsUnrestricted();
++        public void PermitOnly();
++        public IPermission RemovePermission(Type permClass);
++        protected virtual IPermission RemovePermissionImpl(Type permClass);
++        public static void RevertAssert();
++        public IPermission SetPermission(IPermission perm);
++        protected virtual IPermission SetPermissionImpl(IPermission perm);
++        void System.Runtime.Serialization.IDeserializationCallback.OnDeserialization(object sender);
++        public override string ToString();
++        public virtual SecurityElement ToXml();
++        public PermissionSet Union(PermissionSet other);
++    }
+ }
+```
+