bug#19537: Manual documents nonexistent functionality of package-upload-buffer

[Kelly Dean <kelly@prtime.org>]

Manual page «(elisp) Package Archives» says:
⌜ -- Command: package-upload-buffer
     This command is similar to `package-upload-file', but instead of
     prompting for a package file, it uploads the contents of the
     current buffer.  The current buffer must be visiting a simple
     package (a `.el' file) or a multi-file package (a `.tar' file);
     otherwise, an error is raised.⌝

But in fact, it must be visiting a simple package; it can't be a multi-file package. For the latter, only package-upload-file works (and even that works only after the patch for bug #19536 is applied).