Update security policy for 1.x and 2.x (Qiskit#14081)

* Update security policy for 1.x and 2.x

With the 1.x release we're extending security support for Qiskit to 1
yr. We still only support 1.x for general bugfixes for 6 months after
the 2.0.0 release. But for 1.x if any security vulnerabilities are
identified we will provide fixes for that up to 1 yr after the release
of 2.0.0. This was reflected in the 1.4.0 release notes and is on the
version strategy docs:

https://docs.quantum.ibm.com/open-source/qiskit-sdk-version-strategy

but we forgot to update the security policy document in the Qiskit repo.
This commit fixes this oversight.

* Update SECURITY.md

Co-authored-by: Elena Peña Tapia <[email protected]>

---------

Co-authored-by: Elena Peña Tapia <[email protected]>

Author: mtreinish

SECURITY.md

@@ -4,11 +4,13 @@
 
 Qiskit supports the most recent major release with new features, which will only appear in minor releases of that series.
 The most recent minor release in the current major release series is also supported with bug fixes.
-In addition, the last minor release of the *previous* major release series is supported with bug fixes for six months after a new major release.
+In addition, the last minor release of the *previous* major release series is supported with bug fixes for six months after a new major release,
+and one year of security fixes.
 
 For example, if the most recent release is 1.0.1, then the current major release series is 1.x and the current minor release is 1.0.x.
 The 1.0.x series will be supported with bug fixes, until the release of 1.1.0, which will include new features.
-The last version of the previous major release, 0.46.x, is supported with bugfixes only until six months after the final release of 1.0.0.
+The last version of the previous major release, 0.46.x, is supported with bug fixes until six months after the final release of 1.0.0,
+and for one year with any security fixes.
 
 We provide more detail on [the release and support schedule of Qiskit in our documentation](https://docs.quantum.ibm.com/open-source/qiskit-sdk-version-strategy).