Bind9: man file for rndc utility mentions wrong config file location

Man page for the rndc utility mentions that /etc/rndc.key and /etc/rndc.conf are default locations for config files. That is not true.

> man rndc
```
       -c config-file
           Use config-file as the configuration file instead of the default, /etc/rndc.conf.

       -k key-file
           Use key-file as the key file instead of the default, /etc/rndc.key. The key in /etc/rndc.key will be used to authenticate commands sent to the server if the config-file does not exist.

```

In fact, running rndc with strace shows that it looks for these files at /etc/bind
```
futex(0x7ff0e3472028, FUTEX_WAKE_PRIVATE, 1) = 1
stat("/etc/bind/rndc.conf", 0x7ffe2b70d1e0) = -1 ENOENT (No such file or directory)
stat("/etc/bind/rndc.key", {st_mode=S_IFREG|0640, st_size=77, ...}) = 0
openat(AT_FDCWD, "/etc/bind/rndc.key", O_RDONLY) = 6
```

# Suggested resolution:
update the man page so it is not misleading.

Use case: on my configuration, Bind9 is configured to listen on 127.0.0.2 because I use another DNS server that handles most traffic at 127.0.0.1. But I could not get rndc to talk to correct ip address regardless of what I wrote at /etc/rndc.conf. Finally, strace revealed that the expected config file location is different from what man page tells. I've spent a considerable amount of time debugging what is wrong with my configuration

# System and version information:

Ubuntu 18.04

Package: bind9
Version: 1:9.11.3+dfsg-1ubuntu1.13