Several README tidies
Several README tidies

* Do not specify the directory in which to find the target executable.
The specified directory went away when we fixed our Makefile a year or so
ago. People who want to try development in Rust will know where to find the
generated executable, which will vary in its location depending on how they
built it.

* Get rid of the --help option sentence. Users are ever hopefull about the
--help option, and don't really needed to be reminded about something so
customary.

* Get rid of the explanations of dependencies and just link to the ci
dependency install script.

Signed-off-by: mulhern <7b51bcf507bcd7afb72bf8663752c0ddbeb517f6@redhat.com>

stratis-storage/stratisd,stratis-storage/stratisd,stratis-storage/stratisd