doc: op-build v1.21.2 release notes

Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
diff --git a/doc/release-notes/index.rst b/doc/release-notes/index.rst
index 1912751..b06ec9d 100644
--- a/doc/release-notes/index.rst
+++ b/doc/release-notes/index.rst
@@ -10,3 +10,5 @@
    v1.21-rc2
    v1.21
    v1.21.1
+   v1.21.2
+
diff --git a/doc/release-notes/v1.21.2.rst b/doc/release-notes/v1.21.2.rst
new file mode 100644
index 0000000..0042d87
--- /dev/null
+++ b/doc/release-notes/v1.21.2.rst
@@ -0,0 +1,15 @@
+Release Notes for OpenPower Firmware v1.21.2
+============================================
+
+This is a point release on top of op-build v1.21.
+
+Like v1.21, this release is NOT intended for GA POWER9 platforms, for that,
+op-build v2.0 is *required*.
+
+Changes since v1.21.1:
+
+- skiboot 5.10.2
+
+  - Tie tm-suspend fw-feature and opal_reinit_cpus() together
+
+- kernel: Move to Linux 4.14.24-openpower1