Adds a new site option and returns the ID of the inserted post in the table (wp_sitemeta).
Existing site options will not be updated by this function.
NB: Prior to WordPress 3.3 this was not the case. Previously this function would overwrite an option of the same name which already existed. You may have to be careful to check that the option does not already exist if you do not want to overwrite it.
<?php add_site_option($key, $value); ?>
To get the value that has been set is done by using the function WPMU_Functions/get_site_option.