brdc file downloading now requires registration

[wushangwei]

According to the announcement by nasa, brdc file is not available directly over unencrypted ftp:

US Government security requirements no longer permit CDDIS to offer data via traditional unencrypted anonumous ftp; this service was discontinued on October 31, 2020. All data are still available, however access must be via HTTPS or ftp-ssl.

Instructions` with examples and our FAQ can be found at: https://cddis.nasa.gov/Data_and_Derived_Products/CDDIS_Archive_Access.html.

If you still have difficulty after reading and attempting the examples on that page, please contact us at [email protected].

Daily brdc file is available at https://cddis.nasa.gov/archive/gnss/data/daily and requires a simple registration. Please update README for that. Thank you!

[osqzss]

I would be grateful if you would write a new README for us and send me a pull request!