Merge bitcoindevkit/bdk#1289: doc(electrum_ext): fix docs for `RelevantTxids::into_co...

cf0c3337446b1de19ad6be9e68f5a9cb848d5773 doc(electrum_ext): fix docs for `RelevantTxids::into_confirmation_time_tx_graph` (vmammal)

Pull request description:

  Note also, the bit referring to Electrum's API sounds more like a developer note, so I made it a regular code comment.

  ### Checklists

  #### All Submissions:

  * [x] I've signed all my commits
  * [x] I followed the [contribution guidelines](https://github.com/bitcoindevkit/bdk/blob/master/CONTRIBUTING.md)
  * [x] I ran `cargo fmt` and `cargo clippy` before committing

ACKs for top commit:
  danielabrozzoni:
    ACK cf0c3337446b1de19ad6be9e68f5a9cb848d5773

Tree-SHA512: 0ebd6a753c8a0c573510a4d866068cb6e1c7e356c43b20b5179331a1b7d567e4dfbf7012c63ba9b7b9566bf6564a2d957d12e54d5c0232b7be9869dfe0958e85

diff --cc crates/electrum/src/electrum_ext.rs
Simple merge