Update page_creation.rst

Apache's directory index documentation link outdated - replaced <2.0> in the link with <2.4>
Update page_creation.rst
minor #3820 Update page_creation.rst (adreeun)

This PR was submitted for the 2.4 branch but it was merged into the 2.3 branch instead (closes #3820).

Discussion
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Update page_creation.rst

Apache's directory index documentation link outdated - replaced <2.0> in the link with <2.4>

Commits
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32508f2 Update page_creation.rst
e0cb998 Update page_creation.rst