Doc fix.

Author: patrick-kidger

diffrax/brownian/tree.py

@@ -202,10 +202,9 @@ def _body_fun(_state):
 - `t1`: The start of the interval the Brownian motion is defined over.
 - `tol`: The discretisation that `[t0, t1]` is discretised to.
 - `shape`: Should be a PyTree of `jax.ShapeDtypeStruct`s, representing the shape, 
-dtype, and PyTree structure of the output. For simplicity, `shape` can also just 
-be a tuple of integers, describing the shape of a single JAX array. In that case
-the dtype is chosen to be `float64` if `JAX_ENABLE_X64=True` and `float32` 
-otherwise.
+    dtype, and PyTree structure of the output. For simplicity, `shape` can also just 
+    be a tuple of integers, describing the shape of a single JAX array. In that case
+    the dtype is chosen to be the default floating-point dtype.
 - `key`: A random key.
 
 !!! info