Add helpful hints to the ARM about generating pin files for HSMs when using BIND build with --enable-native-pkcs11

It may not be true of all HSM providers and their PKCS#11 lib, but in at least one instance we've encountered, how you generate the pin file is very significant - having a trailing newline or similar will make the difference between the pin being accepted or the authentication failing.

Examples of how to generate an HSM pin file without a newline:

$ echo -n 1234 > hsmpin

or

$ printf 1234 > hsmpin

Easily verified as being clean of any additional characters using wc:

$ wc -l < hsmpin
       0

or

$ wc < hsmpin
       0       1       4

(The wc order of output always takes the form of line, word,byte, and file name.)

For comparison, this is a pin file that was not accepted by an HSM because 'echo' without -n adds the newline by default in this particular test environment:

$ echo 1234 > hsmpin
$ wc -l < hsmpin
       1
$ wc < hsmpin
       1       1       5

(From Support ticket #14117 )