add datasets to data.md (#540)

added links and general info for interesting example datasets to use with cellxgene

docs/data.md

@@ -0,0 +1,29 @@
+---
+layout: default
+title: data
+description: Data
+---
+
+
+# data vignette: how to use cellxgene prepare
+
+#### coming soon!
+
+# example datasets to use with cellxgene
+
+### Examination of single cells from primary human pancreas tissue
+cells: 2,544  
+tissue(s): pancreas  
+data: [GEO Series GSE81547](https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE81547)  
+paper: [Enge, Martin, et al.](https://www.cell.com/cell/fulltext/S0092-8674(17)31053-X?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS009286741731053X%3Fshowall%3Dtrue)
+
+### Tabula Muris
+cells: 53,800  
+tissue(s): muscle, pancreas, bone, large intestine, heart, brain, fat, mammary gland, tongue , diaphragm, bladder, spleen, thymus, lung , skin, liver, trachea, kidney  
+data: [Tabula Muris Data for Python](https://github.com/czbiohub/tabula-muris-vignettes/tree/master/data)  
+paper: [Tabula Muris Consortium.](https://www.nature.com/articles/s41586-018-0590-4)  
+
+### Transcriptional profiling of 1.3 million brain cells
+cells: 1,330,000  
+tissue(s): brain  
+data: [10x Genomics](https://community.10xgenomics.com/t5/10x-Blog/Our-1-3-million-single-cell-dataset-is-ready-to-download/ba-p/276)