1.7.1 Release notes first pass

We'll need to move the current release notes in master for 1.7.1 to 1.8.0 since
they were not included in this release at this time and cherry-pick
these notes into master.

docs/releases/1.7.1.md

@@ -0,0 +1,12 @@
+*Please see [1.7-NOTES.md](1.7-NOTES.md) for known issues, significant changes, and required actions for 1.7.*
+
+This document describes the changes since 1.7.0.
+
+# Significant changes
+
+* kube-dns has been updated with the hotfix for CVE-2017-14491.  For more details, please see [CVE Advisory](kops/docs/advisories/cve_2017_14491.md).
+
+# Full changelist
+
+* Update images in CI tests (thanks @justinsb)
+* Update kube-dns to 1.14.5 for CVE-2017-14491 (thanks @mikesplain)