Core Metadata: Add example of multiple emails (pypa#429)

Author: di

source/specifications/core-metadata.rst

@@ -292,6 +292,11 @@ Example::
 
     Author-email: "C. Schultz" <[email protected]>
 
+Per RFC-822, this field may contain multiple comma-separated e-mail
+addresses::
+
+    Author-email: [email protected], [email protected]
+
 
 Maintainer (optional)
 =====================
@@ -328,6 +333,11 @@ Example::
 
     Maintainer-email: "C. Schultz" <[email protected]>
 
+Per RFC-822, this field may contain multiple comma-separated e-mail
+addresses::
+
+    Maintainer-email: [email protected], [email protected]
+
 
 License (optional)
 ==================