Update docs and remove some detector modules from init

doc/getting_started.rst

@@ -15,10 +15,10 @@ If the toolbox has been installed in your home directory previously, everything
 
 .. code:: bash
 
-    pip install --user .
+    pip install --user ".[maxwell]"
 
 Alternatively, use the -e flag for installation to install the package in development mode.
 
 .. code:: bash
 
-    pip install --user -e .
+    pip install --user -e ".[maxwell]"

src/toolbox_scs/detectors/__init__.py

@@ -4,9 +4,7 @@ from .digitizers import *
 from .dssc import *
 from .dssc_data import *
 from .dssc_misc import *
-from .dssc_plot import *
 from .dssc_processing import *
-from .fccd import *
 from .xgm import *
 
 __all__ = (