peltool: Add Notes from message registry file

Add the Notes section found in the message registry file to the json
output (if it's present and not empty).

Example:

"Error Details": {
    "Message":  "Unknown (Original event not in message registry)",
    "Notes": [
                "This is used when the actual error name isn't",
                "found in the registry."
    ]
}

Signed-off-by: Harisuddin Mohamed Isa <harisuddin@gmail.com>
Change-Id: I69773547c06f6361055c2f0decd07967d0012946
diff --git a/extensions/openpower-pels/registry.cpp b/extensions/openpower-pels/registry.cpp
index c8c37f9..523a15b 100644
--- a/extensions/openpower-pels/registry.cpp
+++ b/extensions/openpower-pels/registry.cpp
@@ -680,7 +680,12 @@
             entry.doc.description = doc["Description"];
             if (doc.contains("MessageArgSources"))
             {
-                entry.doc.messageArgSources = doc["MessageArgSources"];
+                entry.doc.messageArgSources =
+                    doc["MessageArgSources"].get<std::vector<std::string>>();
+            }
+            if (doc.contains("Notes") && !doc["Notes"].empty())
+            {
+                entry.doc.notes = doc["Notes"].get<std::vector<std::string>>();
             }
 
             // If there are callouts defined, save the JSON for later