Reduce SECURITY.md to just point to TensorFlow SECURITY.md. (#6757)

Googlers, see b/325155004.

Author: bmd3k

SECURITY.md

@@ -2,9 +2,4 @@
 
 Please refer to [TensorFlow’s security model and guidelines][tf-security].
 
-To report any security related issues, please email `[email protected]`
-[as described in TensorFlow’s `SECURITY.md`][email]. Consult that document for
-details, including an encryption key for especially sensitive disclosures.
-
-[email]: https://github.com/tensorflow/tensorflow/blob/master/SECURITY.md#reporting-vulnerabilities
 [tf-security]: https://github.com/tensorflow/tensorflow/blob/master/SECURITY.md