added TP_ADDON to Plex mod

docker-mods/plex/root/etc/cont-init.d/98-themepark

@@ -41,4 +41,8 @@ if ! grep -q "${TP_DOMAIN}" "${APP_FILEPATH}"; then
     sed -i "s/<\/head>/<link rel='stylesheet' href='https:\/\/${TP_DOMAIN}\/CSS\/themes\/plex\/plex-base.css'><\/head> /g" "${APP_FILEPATH}"/usr/lib/plexmediaserver/Resources/Plug-ins-*/WebClient.bundle/Contents/Resources/index.html
     sed -i "s/<\/head>/<link rel='stylesheet' href='https:\/\/${TP_DOMAIN}\/CSS\/variables\/${TP_THEME}.css'><\/head> /g" "${APP_FILEPATH}"/usr/lib/plexmediaserver/Resources/Plug-ins-*/WebClient.bundle/Contents/Resources/index.html
     printf 'Stylesheet set to %s\n' "${TP_THEME}"
+    if [[ -n ${TP_ADDON} ]]; then
+        sed -i "s/<\/head>/<link rel='stylesheet' href='https:\/\/${TP_DOMAIN}\/CSS\/addons\/plex\/${TP_ADDON}\/${TP_ADDON}.css'><\/head> /g" "${APP_FILEPATH}"/usr/lib/plexmediaserver/Resources/Plug-ins-*/WebClient.bundle/Contents/Resources/index.html
+        printf 'Added custom addon: %s\n\n' "${TP_ADDON}"
+    fi
 fi