Fixed bug in the example of using apt-key

Original error:
$ sudo apt-key adv --keyserver keyserver.ubuntu.com --recv E0C56BD4
Executing: /tmp/apt-key-gpghome.g8OJxK1FMy/gpg.1.sh --keyserver keyserver.ubuntu.com --recv E0C56BD4
gpg: keyserver receive failed: Server indicated a failure

website/index.html

@@ -404,7 +404,7 @@
     <code id="packages-install">
 <pre>
 sudo apt-get install dirmngr    # optional
-sudo apt-key adv --keyserver keyserver.ubuntu.com --recv E0C56BD4    # optional
+sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv E0C56BD4    # optional
 
 echo "deb http://repo.yandex.ru/clickhouse/deb/stable/ main/" | sudo tee /etc/apt/sources.list.d/clickhouse.list
 sudo apt-get update