This was reported through the mailing list.
The source is at hadoop-common-project/hadoop-common/src/site/markdown/ClusterSetup.md.
> On Sat, May 9, 2015 at 1:10 PM, 有江香織 <email@example.com> wrote:
>> To whom this may concern,
>> I found a dead link and typo.
>> Could I ask you to help me out with fixing that problem?
>> + dead link: http://www.apache.org/contact.html
>> + typo:
>> + before: YARN damones
>> + after: YARN daemons