Update tolerance docstring to reflect precision-dependent default.

Author: duburcqa

genesis/options/solvers.py

@@ -435,7 +435,8 @@ class RigidOptions(Options):
     iterations : int, optional
         Number of iterations for the constraint solver. Defaults to 50.
     tolerance : float, optional
-        Tolerance for the constraint solver. Defaults to 1e-6.
+        Tolerance for the constraint solver. Defaults to None, which is resolved at build time based on the
+        floating-point precision: 1e-5 for single precision (f32) and 1e-8 for double precision (f64).
     ls_iterations : int, optional
         Number of line search iterations for the constraint solver. Defaults to 50.
     ls_tolerance : float, optional