enabled available apache2 code example

Example 1: a2ensite example

a2ensite /etc/apache2/sites-available/new-domain.conf
//-----------------
a2dissite /etc/apache2/sites-available/new-domain.conf

Example 2: a2ensite example.

a2ensite /etc/apache2/sites-available/new-domain.conf

//-----------------

a2dissite /etc/apache2/sites-available/new-domain.conf