Add XML documentation for Org.Apache.Http.Conn.Routing

[jonathanpeppers]

The Org.Apache.Http.Conn.Routing namespace contains 6 To be added placeholders in source XML documentation (excluding docs\xml\index.xml).

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

Update log

• 2026-09-10: Refreshed the placeholder scan from 111 to 6 (reduced by 105). Related documentation PRs: #530, #644.