more info in readme

docker/README.md

 # Docker/Singularity image
 
-This `Dockerfile` bundles required software to run the mosaicatcher pipeline .
+This `Dockerfile` bundles required software to run the mosaicatcher pipeline.
 
 It does not contain
 * `snakemake` (which is required to run the pipeline)
@@ -8,3 +8,14 @@ It does not contain
 * example data
 
 For the later two please see `hg38` and `RPE1-WT_chr3`.
+
+### Availability
+
+* On [dockerhub](https://cloud.docker.com/repository/docker/smei/mosaicatcher-pipeline)
+* Will be automatically downloaded by Snakemake if run in `--use-singularity`
+  mode
+
+### Updates
+
+This image is configured to auto-build on dockerhub, yet it uses a fixed version
+of `mosaicatcher`.
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