Add Prairie Vole atlas to list (#420)

README.md

@@ -40,6 +40,7 @@ A number of atlases are in development, but those available currently are:
 | [Blind Mexican Cavefish Brain Atlas](https://doi.org/10.7554/eLife.80777) | 2 micron | 6 days post fertilisation | IHC | sju_cavefish_2um
 | [BlueBrain Barrel Cortex Atlas](https://doi.org/10.1162/imag_a_00209) | 10 and 25 micron | P56 | STPT | allen_mouse_bluebrain_barrels_10um, allen_mouse_bluebrain_barrels_25um
 | [UNAM Axolotl Brain Atlas](https://doi.org/10.1038/s41598-021-89357-3) | 40 micron | ~ 3 months post hatching | MRI | unam_axolotl_40um
+| [Prairie Vole Brain Atlas](https://doi.org/10.7554/eLife.87029.3.sa0) | 25 micron | Unknown | LSFM | prairie_vole_25um
 
 ## Installation