Add XML documentation for Org.Apache.Http.Protocol

[jonathanpeppers]

The Org.Apache.Http.Protocol namespace contains 172 To be added placeholders in source XML documentation (excluding docs\xml\index.xml).

rg -n -i --glob 'Org.Apache.Http.Protocol/**' --glob 'ns-Org.Apache.Http.Protocol.xml' 'to be added' docs\xml

Update log

• 2026-09-10: Refreshed the placeholder scan from 149 to 172 (increased by 23). Related documentation PRs: #427, #644.