Fix lint and documentation issue from D51906858 (pytorch#2157)

Summary:
Pull Request resolved: pytorch#2157

D51906858 introduced a lint issue and a documentation issue. I'm mystified as to why arc lint did not pick up the lint issue?. In any case, this fixes it.

Reviewed By: saitcakmak

Differential Revision: D52316861

fbshipit-source-id: ab7198de4a93d792ec5f3fde9d6af29371e3e28b

Author: bletham

botorch/utils/multitask.py

@@ -20,10 +20,10 @@
 
 def separate_mtmvn(mvn: MultitaskMultivariateNormal) -> List[MultivariateNormal]:
     """
-    Separate a MTMVN into a list of MVNs, where covariance across data within each task are
-    preserved, while covariance across task are dropped.
+    Separate a MTMVN into a list of MVNs, where covariance across data within each task
+    are preserved, while covariance across task are dropped.
     """
-    # TODO T150340766 Upstream this into a class method on gpytorch MultitaskMultivariateNormal.
+    # T150340766 Upstream as a class method on gpytorch MultitaskMultivariateNormal.
     full_covar = mvn.lazy_covariance_matrix
     num_data, num_tasks = mvn.mean.shape[-2:]
     if mvn._interleaved:

sphinx/source/utils.rst

@@ -37,6 +37,11 @@ Low-Rank Cholesky Update Utils
 .. automodule:: botorch.utils.low_rank
 		:members:
 
+Multi-Task Distribution Utils
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+.. automodule:: botorch.utils.multitask
+		:members:
+
 Objective
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 .. automodule:: botorch.utils.objective