Add release notes page for version 27.0.0

Tempest 27.0.0 has been released [1].
This commit adds a new page for 27.0.0 release notes.

[1] https://review.opendev.org/c/openstack/releases/+/783349

Change-Id: I7f055c9724ce39145125664db8cc8e1fc168314f
diff --git a/releasenotes/source/v27.0.0.rst b/releasenotes/source/v27.0.0.rst
new file mode 100644
index 0000000..0009124
--- /dev/null
+++ b/releasenotes/source/v27.0.0.rst
@@ -0,0 +1,5 @@
+=====================
+v27.0.0 Release Notes
+=====================
+.. release-notes:: 27.0.0 Release Notes
+   :version: 27.0.0