c4d5f2ccd8doc(example_cli): add missing cli docs (vmammal) Pull request description: ### 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: evanlinjin: ACKc4d5f2ccd8Tree-SHA512: 43684abbb32570f07e0dc05ed07062bc7969cbe7c4fefe8ae7ebe41ac28aedfbba76ffc801bc4ddb3bf08a940ca81c128376dc3f6c76a04f1391e43c18e0d50b