update install instructions for 1.2.1

Author: jmrohwer

INSTALL.md

@@ -2,20 +2,24 @@
 
 Binary install packages for all three OSs and recent Python versions are 
 provided. Anaconda packages are available for 64-bit Windows and Linux, as well as 
-macOS *x86_64* architecture. Apple Silicon (*arm64*) macOS users should install with 
-`pip` (see below). Anaconda users can conveniently install PySCeS with:
+macOS *x86_64* and Apple Silicon (*arm64*) architectures. Anaconda users can 
+conveniently install PySCeS with:
 
 ```bash
 $ conda install -c conda-forge -c pysces pysces
 ```  
 
 Any dependencies will be installed automatically, including the optional dependencies 
-*Assimulo*, *ipyparallel* and *libSBML*. 
+*Assimulo*, *ipyparallel* and *libSBML*.
+> **NOTE:** Anaconda packages are only provided for Python versions 3.9-3.11. The 
+> reason is that Assimulo has not been ported to Python 3.12 and still depends on 
+> `numpy.distutils`. As soon as this has happened, PySCeS Anaconda packages for 3.12 
+> will be built.
 
 Alternatively, you can use *pip* to
-install PySCeS from PyPI. Core dependencies will be installed automatically. Wheels 
-are available for 64-bit Windows and Linux, as well as macOS architectures *x86_64* and 
-*arm64* (starting from PySCeS version 1.2.0).
+install PySCeS from PyPI. Core dependencies will be installed automatically. Wheels
+are available for 64-bit Windows and Linux, as well as macOS architectures *x86_64* and
+*arm64* (starting from PySCeS version 1.2.0, supporting Python 3.11 and 3.12).
 
 ```bash
 $ pip install pysces