Added discussion of the Makefile targets to README.

Python/README.md

@@ -19,7 +19,7 @@ You can verify that the installation was successful by trying to import `corsika
 
     python -c 'import corsika'
 
-# Running the Tests
+## Running the Tests
     
 If you wish to develop new features in `corsika`, you will also need to install
 some additional dependencies so you can run our unit tests. These can be
@@ -30,3 +30,27 @@ installed with
 Once that is completed, you can run the unit tests directory from the `corsika` directory
 
     python -m pytest tests
+
+## Development Guide
+
+`corsika` is a type Python package with type-checking using
+[Mypy](mypy-lang.org) and all code is formatted with the
+[Black](https://black.readthedocs.io/en/stable/) formatter.
+
+All code must pass these checks, as well as several others, before it can be
+merged into CORSIKA. A `Makefile` is provided to simplify running these in
+tasks.
+
+    make mypy   # this will run the mypy type checker
+    
+    make isort  # this will automatically sort `import` statements
+    
+    make black  # this will automatically format your code
+    
+    make flake  # this checks that all code passes our linting rules
+    
+    make tests  # this runs our test suite
+    
+Lastly, we provide an `all` target that runs *all* of the above in the sequence shown above:
+
+    make all  # run all of the above tests