Add description and license #335

Job	Run time
test apt (stable)	40s
rustfmt	1m 14s
test apt (beta)	42s
Address sanitizer	1m 28s
test apt (nightly)	37s
conda (ubuntu, conda-forge, stable)	52s
conda (windows, conda-forge, stable)	3m 46s
mpi-runner	1m 32s
conda (macos, conda-forge, stable)	55s
static builds (ubuntu-latest, stable)	1m 14s
static builds (windows-latest, stable-msvc)	6m 49s
static builds (windows-latest, stable-gnu)	5m 41s
static builds (macos-12, stable)	4m 19s
static builds (macos-latest, stable)	1m 29s
	31m 18s

Provide feedback