Update readme with docker/singularity

README.rst

@@ -32,6 +32,15 @@ To get the latest (stable) development release::
 
     pip install git+https://git.km3net.de/km3py/km3io.git
 
+Docker:
+
+    docker run -it docker.km3net.de/km3io
+
+Singularity:
+
+    wget https://sftp.km3net.de/singularity/km3io_v0.27.2.sif  # pick the version you like
+    singularity shell km3io_v0.27.2.sif
+
 **Reminder:** km3io is **not** dependent on aanet, ROOT or Jpp!
 
 Questions