Changes foobar.net in example.com

As recommanded by the RFC 2606, example.com(/net/org) should be used
as they are reserved for this usage.
minor #4115 [Documentation] [Minor] Changes foobar.net in example.com (magnetik)

This PR was submitted for the 2.5 branch but it was merged into the 2.3 branch instead (closes #4115).

Discussion
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[Documentation] [Minor] Changes foobar.net in example.com

As recommanded by the RFC 2606, example.com(/net/org) should be used
as they are reserved for this usage.

Commits
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715c0ed Changes foobar.net in example.com