docs: update cargo features in README to match Cargo.toml

[Musab1258]

Description

The README referenced outdated cargo feature flags kyoto and sp, which will cause build failures for users following the instructions. This commit updates the documentation to use the correct flags cbf and silent-payments as defined in the current Cargo.toml.

Fixes #299

Notes to the reviewers

This is a documentation update to the README.md. I specifically left the reference to Kyoto in the "About" section intact, as it correctly refers to the underlying bdk_kyoto library/concept, and only updated the actual Cargo feature flags in the code blocks and feature lists.

Changelog notice

• Fixed outdated cargo feature flags (kyoto -> cbf and sp -> silent-payments) in the README instructions.

Checklists

All Submissions:

• I've signed all my commits
• I followed the contribution guidelines
• I ran cargo fmt and cargo clippy before committing

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

[Musab1258]

Hi @tvpeter, can you please check this out?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 56.89%. Comparing base (6000dd5) to head (4a1ff1b).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #300   +/-   ##
=======================================
  Coverage   56.89%   56.89%           
=======================================
  Files          22       22           
  Lines        3661     3661           
=======================================
  Hits         2083     2083           
  Misses       1578     1578           

Flag	Coverage Δ
rust	56.89% <ø> (ø)

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[tvpeter]

ACK 4a1ff1b

[va-an]

ACK 4a1ff1b

Not related to this PR, but a possible follow-up: the flags in this example don't match the code - the command uses --scan_key / --spend_key (src/handlers/descriptor.rs), not --scan_public_key / --spend_public_key.