Hi @Vinuraj M,
This Looks like a Documentation bug ,
Can you please try with this URL
wget -O /etc/apt/sources.list.d/ambari.list http://public-repo-1.hortonworks.com/ambari/ubuntu16/2.x/updates/2.6.2.2/ambari.list
Please note I have added 2.6.2.2 in between updates and ambari.list.
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