Add usage docs to README

README.md

@@ -3,5 +3,44 @@
 
 An app for hosting a catalog of OME-Zarr samples: Images and Plates supported.
 
-You provide a list of OME-Zarr URLs and the app loads metadata and displays a
-zoomable thumbnail of the image in a table.
+You provide a list of OME-Zarr samples as a CSV table and the app loads metadata and displays a
+thumbnail of each image in a table.
+
+The apps is deployed at https://ome.github.io/ome-zarr-catalog/.
+You simply need to specify the location of your CSV file after the URL as `?csv=URL_to_your_table.csv.
+
+For example a CSV file like this is hosted in this repo under `public/zarr_samples.csv`.
+
+```
+URL,                                                                   License,    Study,    Date added
+https://uk1s3.embassy.ebi.ac.uk/idr/zarr/v0.4/idr0054A/5025553.zarr,   CC BY 4.0,  idr0054,  2022-06-03
+https://uk1s3.embassy.ebi.ac.uk/idr/zarr/v0.4/idr0076A/10501752.zarr,  CC BY 4.0,  idr0076,  2022-06-21
+https://uk1s3.embassy.ebi.ac.uk/idr/zarr/v0.4/idr0047A/4496763.zarr,   CC BY 4.0,  idr0047,  2022-06-21
+https://uk1s3.embassy.ebi.ac.uk/idr/zarr/v0.4/idr0062A/6001240.zarr,   CC BY 4.0,  idr0062,  2022-06-21
+```
+
+It's raw URL is https://raw.githubusercontent.com/ome/ome-zarr-catalog/main/public/zarr_samples.csv
+and we can use that to display it as a catalog page:
+
+https://ome.github.io/ome-zarr-catalog/?csv=https://raw.githubusercontent.com/ome/ome-zarr-catalog/main/public/zarr_samples.csv
+
+This adds a single `Thumbnail` column to the data in the `CSV` file.
+
+<img src="https://user-images.githubusercontent.com/900055/248266041-cbc4b1a1-79ee-4243-a8a0-150f5b176fdd.png" width="600px" />
+
+
+We can specify which columns from the following list to add:
+
+  - `Version` - Adds a column with the OME-NGFF version
+  - `Axes` - Displays the `axes` of the Image
+  - `shape` - Displays the `shape` of the Zarr data at highest resolution
+  - `chunks` - Displays the `chunks` of the Zarr data at highest resolution
+  - `Wells` - Shows the `Well` count for Plate data
+  - `Fields`- Shows the `Fields` count for Plate data
+  - `Keywords` - Adds `labels` paths, `plate` and/or `bioformats2raw.layout`
+  - `Thumbnail` - Renders the smallest multiscales dataset as a Thumbnail
+
+These can be specified as a URL query string, e.g. `...&columns=Axes,Thumbnail,shape,chunks`
+
+<img src="https://user-images.githubusercontent.com/900055/248266063-80ec63fc-e6df-457e-bd09-567971705c53.png" width="800px" />
+