Since ~/.netrc isn't widely used by most (if any) NNTP and IMAP
clients, we won't read it by default for lei. AFAIK, ~/.netrc
is mainly by FTP clients (e.g. ftp(1) and lftp(1)). wget uses
it by default for HTTP(S) (and FTP), but curl does not.
To avoid breaking stable release use cases, public-inbox-watch
continues to read ~/.netrc by default.
The --netrc switch is supported by all existing lei commands
which may use curl.