Docs: Update spec.rst [skip ci] (#4295)
Docs: Update spec.rst [skip ci] (#4295)

This PR updates `spec.rst` with minor corrections to punctuation and naming convention
jakirkham/dask,blaze/dask,ContinuumIO/dask,blaze/dask,mrocklin/dask,dask/dask,ContinuumIO/dask,dask/dask,mrocklin/dask,jcrist/dask,jakirkham/dask,jcrist/dask