apache2_server_signiture signature vs signiture.

[whataboutpereira]

I found that signature is mistyped as signiture in the variable name.

Fixing it will break some existing playbooks that aren't using the default.

README.md:apache2_server_signiture: 'Off'
README.md:* security_signiture
meta/readme.yml: * security_signiture
defaults/main.yml:apache2_server_signiture: 'Off'
templates/etc/apache2/conf-available/security.conf.j2:ServerSignature {{ apache2_server_signiture }}