Update hostname_pattern.rst

Error in xml
minor #3872 Update hostname_pattern.rst (sofany)

This PR was submitted for the 2.4 branch but it was merged into the 2.3 branch instead (closes #3872).

Discussion
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Update hostname_pattern.rst

Error in xml

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1baf2db Update hostname_pattern.rst
Merge branch '2.3' into 2.4