Apply suggestions from code review

Co-authored-by: ElliottKasoar <45317199+ElliottKasoar@users.noreply.github.com>

Author: harveydevereux

janus_core/cli/md.py

@@ -331,7 +331,7 @@ def md(
         Keyword arguments to pass to post-processing. Default is None.
     correlation_kwargs
         Keyword arguments to pass for on-the-fly correlations. Default is None.
-    seed : Optional[int]
+    seed
         Random seed used by numpy.random and random functions, such as in Langevin.
         Default is None.
     log

janus_core/processing/observables.py

@@ -245,9 +245,9 @@ def __init__(
 
         Parameters
         ----------
-        components : list[str] | None
+        components
             Symbols for returned velocity components, x, y, and z (default is all).
-        atoms_slice : Union[list[int], SliceLike, None]
+        atoms_slice
             List or slice of atoms to observe velocities from.
         """
         ComponentMixin.__init__(self, components={"x": 0, "y": 1, "z": 2})