Pulled in changes to arg_config_manager.py from commit bdb09c7 (PR #87)

Author: harryswift01

CodeEntropy/config/arg_config_manager.py

@@ -25,7 +25,12 @@
     },
     "end": {
         "type": int,
-        "help": "Stop analysing the trajectory at this frame index",
+        "help": (
+            "Stop analysing the trajectory at this frame index. This is "
+            "the frame index of the last frame to be included, so for example"
+            "if start=0 and end=500 there would be 501 frames analysed. The "
+            "default -1 will include the last frame."
+        ),
         "default": -1,
     },
     "step": {