Add Electron Microscopy to Data Standards

[jen-dfci]

Please add Electron Microscopy as a separate set of data standards (new category) with the level 1-4 manifests on the page.

Top of page can have the following table (and bottom should have usual Attributes/Directions section):

| Level | Definition | Example Data |
| 1 | Raw electron microscopy data as one TIFF file per plane for a 3D image stack or per tile for a 2D large area montage | tiff |
| 2 | Processed electron microscopy data as one OME-TIFF image per plane or montage | ome-tiff |
| 3 | Segmented electron microscopy data | am, tiff |
| 4 | Movies or other derived files from electron microscopy data | mp4, csv |