doc: warn about -bind and dedicated Tor socket in tor.md #35428

Fixes #33458

Problem

When -bind is used to specify listening addresses without explicitly including 127.0.0.1:8334=onion, Bitcoin Core does not create a dedicated Tor socket. The automatic onion service is instead routed to the public IPv4 port, making it impossible for the node to distinguish incoming Tor connections from regular IPv4 connections. The result is that -netinfo and getnetworkinfo silently miscount Tor inbound connections as IPv4, with no indication that anything is wrong.

Fix

Add a note to the automatic onion service section of doc/tor.md explaining this behavior and the two ways to avoid it:

• explicitly add -bind=127.0.0.1:8334=onion alongside other -bind entries
• or disable the automatic onion service with -listenonion=0

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Code Coverage & Benchmarks

For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/35428.

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Duplicate of #34892.