Adds contributor guidance for deprecating and removing user-facing features.
The new section covers general deprecation and removal expectations, then adds category-specific notes for RPCs, startup options and configuration settings, REST/ZMQ interfaces, wallet settings, and IPC/multiprocess interfaces.
Closes #31980.
Tests:
git diff --check( cd ./test/lint/test_runner/ && RUST_BACKTRACE=1 cargo run -- --lint=markdown --lint=trailing_whitespace --lint=trailing_newline --lint=doc )
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For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/35244.
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Thank you for your contribution. The description is too wordy in my eyes and contains instructions that don't make sense for this project, which makes me think it was written by an LLM. I think this kind of instruction should be written by a developer with a lot of experience in the project instead. Closing this for now.