Update Documentation: pointsWrittenDropped what does it mean

The documentation is not clear - what does pointsWrittenDropped mean in httpd context? There are multiple question on stackoverflow and web, does it mean the httpd engine is dropping points, or the written points are dropped because of retention policy?

Locate the documentation entry for pointsWrittenDropped and read its surrounding explanation of the httpd context. Update the documentation so the metric's meaning is explicit, including whether it reflects dropped writes or retention-policy behavior.

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