* Update changelog for 0.4.0 release
* Enable rt feature for irq example in Cargo.toml
* Bump pio/pio-proc deps to 0.2.0, update pio examples
* Update BSPs to latest ws2812-pio, remove unused pio dep
* Fix usage of pio_proc in doc comment
* Clean up pio doc-example
* Update rp-pico to latest i2c-pio
Co-authored-by: Jan Niehusmann <jan@gondor.com>