adding notes and reference for gpg usage

[netskink]

This is a section for usage.

[IgorTodorovskiIBM]

@HarithaIBM are you ok with this one?

[HarithaIBM]

@netskink Hi John, thank you for this PR. Changes looks good just wanted to confirm if you have tested--auto-key-locate and --edit-key options? Apart from these 2 , i had covered rest in my initial testing phase.

[netskink]

Hello Haritha,

The gen key part works. Excellent work Harithia. You rock the roll!

$ cd ~
$ rm -rf .gnupg
$ zopen upgrade meta -y
$ zopen upgrade -y
$ zopen  remove gpg -y
$ zopen install gpg
$ gpg --gen-key             <---- This works now.  Yay!

The next command, has an issue.

$ gpg --armor --output mypubkey.gpg --export [email protected]
gpg: can't mmap pool of 32768 bytes: EDC5128I No such device. - using malloc
gpg: Please note that you don't have secure memory on this system
gpg: WARNING: unsafe permissions on homedir '/z/jd895801/.gnupg'

I'm not certain what the device is that is trying to map. As far the ~/.gnupg dir goes, its permissions are:
755. Should it be 700?