Merge bitcoindevkit/bdk#1220: chore: fix typos and remove unused speculos dockerfiles

27a63abd1e7c87aaf3e07f8023370887a270c61a chore: typos fixed (Einherjar)

Pull request description:

  ### Description

  Fixes the typos and remove unused speculos dockerfiles that was done in #1165.
  Moving these changes into this PR to be merged first.
  Then, we can rebase #1165 and make it only related to CI and Nix.
  (Maybe do a big squash 😄)

  ## Note to Reviewers

  About the speculos stuff, we are not using them, removed in #793,
  more specifically in 3f5a78ae3b1e6c3f0a6acc98bb2445c895cfd743.

  ### Changelog notice

  - Fix typos in codebase and docs
  - Remove unused CI tests with hardware signer Dockerfiles

  ### 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

  #### New Features:

  * [ ] I've added tests for the new feature
  * [ ] I've added docs for the new feature

  #### Bugfixes:

  * [ ] This pull request breaks the existing API
  * [ ] I've added tests to reproduce the issue which are now passing
  * [ ] I'm linking the issue being fixed by this PR

ACKs for top commit:
  danielabrozzoni:
    ACK 27a63abd1e7c87aaf3e07f8023370887a270c61a

Tree-SHA512: a01101d0741e2b0e1d1254b5cae670c5a936bb0b89332c102feb57d58d2b9ae995ed4436068b0dc5fae73dbe22431c3143d6e04cdc12eab991bd726cfd2fbe25