[docs] Remove incorrect information about lit.

Lit does support redirects in the 2>&1 style.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177403 91177308-0d34-0410-b5e6-96231b3b80d8

docs/TestingGuide.rst

@@ -224,16 +224,7 @@ Below is an example of legal RUN lines in a ``.ll`` file:
     ; RUN: diff %t1 %t2
 
 As with a Unix shell, the RUN lines permit pipelines and I/O
-redirection to be used. However, the usage is slightly different than
-for Bash. In general, it's useful to read the code of other tests to figure out
-what you can use in yours. The major differences are:
-
--  You can't do ``2>&1``. That will cause :program:`lit` to write to a file
-   named ``&1``. Usually this is done to get stderr to go through a pipe. You
-   can do that with ``|&`` so replace this idiom:
-   ``... 2>&1 | FileCheck`` with ``... |& FileCheck``
--  You can only redirect to a file, not to another descriptor and not
-   from a here document.
+redirection to be used.
 
 There are some quoting rules that you must pay attention to when writing
 your RUN lines. In general nothing needs to be quoted. :program:`lit` won't