Update bdk 0.30.x README docs to deprecate the bdk library

[notmandatory]

Description

This is needed to direct new and existing users to upgrade to the new bdk_wallet1.0 library.

I also used this PR to bump the version and changelog to v0.30.1 so we're ready to publish the fix in #1782.

Checklists

All Submissions:

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

[oleonardolima]

cACK f549745

[oleonardolima]

Should another mention of the latest bdk_wallet be added to docs, so it appears on docs.rs too?

bdk/src/lib.rs

Lines 22 to 33 in f549745

	//! A modern, lightweight, descriptor-based wallet library written in Rust.
	//!
	//! # About
	//!
	//! The BDK library aims to be the core building block for Bitcoin wallets of any kind.
	//!
	//! * It uses [Miniscript](https://github.com/rust-bitcoin/rust-miniscript) to support descriptors with generalized conditions. This exact same library can be used to build
	//! single-sig wallets, multisigs, timelocked contracts and more.
	//! * It supports multiple blockchain backends and databases, allowing developers to choose exactly what's right for their projects.
	//! * It is built to be cross-platform: the core logic works on desktop, mobile, and even WebAssembly.
	//! * It is very easy to extend: developers can implement customized logic for blockchain backends, databases, signers, coin selection, and more, without having to fork and modify this library.
	//!

[notmandatory]

This needs to be rebased after #1782 is merged (and fixes CI issues). Done.

[thunderbiscuit]

ACK 6d2e243.