Add warning to readme (#30)

README.md

@@ -3,6 +3,12 @@
 ![Actions](https://github.com/qupath/qubalab/actions/workflows/tests.yml/badge.svg?dummy=1234)
 # QuBaLab
 
+> # :warning: Important! 
+> * :new: **This is a new Python package for interacting with QuPath**!
+> * :construction: **It's still being developed and is not yet available on PyPi or conda - it's currently intended only for testing**
+> * :computer: **For a stable, established solution, check out [paquo](https://github.com/Bayer-Group/paquo/) (although we aim to meet different needs, see below)**
+> * :bug: **Please report any bugs through the [issues page](https://github.com/qupath/qubalab/issues)**
+
 
 This is a Python package for exploring quantitative bioimage analysis... *especially* (but not exclusively) in combination with QuPath (https://qupath.github.io/).