Update docs reference on ignite.apache.org to the version 2.0.0

[Vladimir Ozerov]

Hi Mauricio,

As we've released Apache Ignite 2.0, may I ask you to update version of our
docs to 2.0.0 as per post-release step 3 on "Release Process" page [1]?

Regards,
Vladimir

[1] https://cwiki.apache.org/confluence/display/IGNITE/Release+Process