pel: fail boot on host errors

Document requirement that host PELs should cause the boot to fail if the
QuiesceOnHwError setting is enabled

Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
Change-Id: I917dc87cce4dc0e12a6fe13d961373053d0d9a8e
diff --git a/extensions/openpower-pels/README.md b/extensions/openpower-pels/README.md
index c11185a..59812a8 100644
--- a/extensions/openpower-pels/README.md
+++ b/extensions/openpower-pels/README.md
@@ -13,6 +13,7 @@
 * [D-Bus Interfaces](#d-bus-interfaces)
 * [PEL Retention](#pel-retention)
 * [Adding python3 modules for PEL UserData and SRC parsing](#adding-python3-modules-for-pel-userdata-and-src-parsing)
+* [Fail Boot on Host Errors](#fail-boot-on-host-errors)
 
 ## Passing PEL related data within an OpenBMC event log
 
@@ -582,3 +583,17 @@
         jsonStr = json.dumps(d)
         return jsonStr
     ```
+
+## Fail Boot on Host Errors
+
+The fail boot on hw error [design][1] provides a function where a system owner
+can tell the firmware to fail the boot of a system if a BMC phosphor-logging
+event has a hardware callout in it.
+
+It is required that when this fail boot on hardware error setting is enabled,
+that the BMC fail the boot for **any** error from the host which satisfies the
+following criteria:
+- not SeverityType::nonError
+- has a callout of any kind from the `FailingComponentType` structure
+
+[1]: https://github.com/openbmc/docs/blob/master/designs/fail-boot-on-hw-error.md