Move inherits keyword from errors.yaml to metadata.yaml

The metadata.yaml file is the correct location for the inherits.
Update the elog-gen.py parser to support this change.

Change-Id: Iac7f67ec72e761ab3dafbf89c7e4d5495b34f00d
Signed-off-by: Adriana Kobylak <anoo@us.ibm.com>
diff --git a/tools/example/xyz/openbmc_project/Example/Bar.metadata.yaml b/tools/example/xyz/openbmc_project/Example/Bar.metadata.yaml
index ceebffd..bc7381a 100644
--- a/tools/example/xyz/openbmc_project/Example/Bar.metadata.yaml
+++ b/tools/example/xyz/openbmc_project/Example/Bar.metadata.yaml
@@ -3,3 +3,5 @@
   meta:
     - str: "BAR_DATA=%s"
       type: string
+  inherits:
+    - Foo