Add installation script gets latest mkcert release

[ilyar]

./get.sh --help
Installation script gets latest mkcert release for platform and makes runnable binary

Run options:

    -d, --debug                  debug and trace mode
    -n, --no-verify-signature    skip verify signature
    -i, --install-dir="pwd"      accepts a target installation directory
    -h, --help                   display this help and exit

By default verify gpg signature.

info: about gpg https://rvm.io/rvm/security

TODO

• make public GPG key mkcert.asc.
• add sing file of pre-built binaries %binFile%.sig to reliase page.

[FiloSottile]

Hi, thanks for your PR.

Unfortunately, I truly don't believe in stable PGP keys, and I would rather encourage users to use their package manager, which they already trust.

The pre-built binaries are provided as a convenience, but I'm not very interested in making them a first-class installation method, nor have I received reports of them being too hard to use.

[ilyar]

Thank you for your reply.