CI was not building the a.rs application due to the requirement of b.bin
having been built first. Add a feature flag to examples so that CI can
build them including a dummy application.
Update a.rs application examples so that they compile again.
* Remove the need for generic const expressions and use buffers provided in the flash config.
* Extend embedded-storage traits to simplify generics.
* Document all public APIs
* Add toplevel README
* Expose AlignedBuffer type for convenience.
* Update examples