Anatomical Structures, Cell Types, plus Biomarkers (ASCT+B) table for Brain, v1.6

Brain v1.6 is a minor update of the table correcting PCL labels for precursor oligodendricytes and updates citation<br>formats. [Brain v1.5](https://cdn.humanatlas.io/hra-releases/v2.0/asct-b/asct-b-allen-brain.csv) is a minor update of<br>the table that provides parent cell type mappings to Cell Ontology for the specific cell types that were added to<br>[Brain v1.4](https://cdn.humanatlas.io/hra-releases/v1.4/asct-b/asct-b-allen-brain.csv), but do not yet have Cell<br>Ontology (CL) or Provisional Cell Ontology (PCL) IDs. More of the brain anatomy was also mapped to the Uberon<br>multispecies anatomy ontology based on exact matching synonym terms.