rate_limit key is different for json versus text

[reedjc]

See dnsdb_write_info code:
1618 fprintf(stdout, "quota:\n");

The key for -I for default or -p text is "quota" but with -p json it is "rate".
{
"rate": {
...
To be consistent, use "rate:" for default text info output.

[vixie]

fixed in 7d1f2e5..83b3251