Merge bitcoindevkit/bdk-cli#246: doc: add installation prerequisite to Readme

072572456073c174c728a7fa57c601ed69340856 docs: Update stated bdk_wallet version (Vihiga Tyonum)
d787fa03a748ff28048cf7143fad585fe89e48aa doc: added prerequisites to readme (oscar)

Pull request description:

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  ### Description

  This is a continuation of #221

  <!-- Describe the purpose of this PR, what's being adding and/or fixed -->

  ### Notes to the reviewers

  <!-- In this section you can include notes directed to the reviewers, like explaining why some parts
  of the PR were done in a specific way -->
  - Update the stated `bdk_wallet` to 2.x.x
  - Addressed review comments on #221

  ## Changelog notice

  <!-- Notice the release manager should include in the release tag message changelog -->
  <!-- See https://keepachangelog.com/en/1.0.0/ for examples -->

  ### Checklists

  #### All Submissions:

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

ACKs for top commit:
  notmandatory:
    ACK 072572456073c174c728a7fa57c601ed69340856

Tree-SHA512: a0446a915c8c2553ea4612d9e2382e8d3212c73929be9944c9cb965f0fbf2620df339d3284796cf7315bdb65ca5a364a299ba8bfacb3edd3694c2bd796b0fae0