tweaks

doc/source/csst_common/csst_common.rst

@@ -3,13 +3,14 @@ Using ``csst_common``
 
 Some usages of the functions / classes in ``csst_common``. (To be updated)
 
-``CsstMsDataManager``
----------------------
+``csst_common.data_manager.CsstMsDataManager``
+----------------------------------------------
 
 A class that helps developers to access simulation files.
 
 .. code-block:: python
 
+    from csst_common.data_manager import CsstMsDataManager
     # for full basic initialization
     dm_mbi = CsstMsDataManager(
         ver_sim="C5.2",                 # version of simulation, "C5.2" is the latest