Flag constants fix

• adresses #495 and fixes issue
• adds reported bug as test case

saqc/funcs/constants.py

@@ -54,13 +54,13 @@ class ConstantsMixin:
         window :
             Size of the moving window. This determines the number of observations used
             for calculating the absolute change per window.
-            Each window will be of either of a fixed number of periods (integer defined window),
+            Each window will either contain a fixed number of periods (integer defined window),
             or will have a fixed temporal extension (offset defined window).
 
         min_periods :
             Minimum number of observations in window required to generate
-            a flag. This is only to exclude underpopulated *offset* defined windows from
-            flagging.
+            a flag. This can be used to exclude underpopulated *offset* defined windows from
+            flagging. (Integer defined windows will always contain exactly *window* samples).
             Must be an integer greater or equal `2`, because a
             single value would always be considered constant.
             Defaults to `2`.