Add index reference to mailbox module; also remove comment that it's
undocumented (it has been).
collection of ``email headers'' as defined by the Internet standard
RFC 822. It is used in various contexts, usually to read such headers
from a file.
+\index{RFC!822}
-(Note that there's a separate, currently undocumented, module to read
-Unix style mailbox files: \code{mailbox}.)
+Note that there's a separate module to read \UNIX{}, MH, and MMDF
+style mailbox files: \code{mailbox}.
+\refstmodindex{mailbox}
A \code{Message} instance is instantiated with an open file object as
parameter. The optional \code{seekable} parameter indicates if the
collection of ``email headers'' as defined by the Internet standard
RFC 822. It is used in various contexts, usually to read such headers
from a file.
+\index{RFC!822}
-(Note that there's a separate, currently undocumented, module to read
-Unix style mailbox files: \code{mailbox}.)
+Note that there's a separate module to read \UNIX{}, MH, and MMDF
+style mailbox files: \code{mailbox}.
+\refstmodindex{mailbox}
A \code{Message} instance is instantiated with an open file object as
parameter. The optional \code{seekable} parameter indicates if the