move luci specific index.html from package 'sgi-cgi' to 'admin-core'

Contributed by T-Labs, Deutsche Telekom Innovation Laboratories

Signed-off-by: Mirko Vogt <redacted>

diff --git a/libs/sgi-cgi/htdocs/index.html b/modules/admin-core/root/www/index.html
similarity index 100%
rename from libs/sgi-cgi/htdocs/index.html
rename to modules/admin-core/root/www/index.html