Clean up the "docs".
diff --git a/PCbuild/rt.bat b/PCbuild/rt.bat
index 1d2829f..00efe93 100755
--- a/PCbuild/rt.bat
+++ b/PCbuild/rt.bat
@@ -1,11 +1,20 @@
@rem Run Tests. Run the regression test suite.
-@rem Plain "rt" runs Release build, arguments passed on to regrtest.
-@rem "rt -d" runs Debug build similarly, after shifting off -d.
-@rem Normally the tests are run twice, the first time after deleting
-@rem all the .py[co] files from Lib/ and Lib/test/. But
-@rem "rt -q" (for Quick) runs the tests just once, and without
-@rem bothering to delete .py[co] files.
-@rem "rt -O" runs python or python_d with -O (depending on -d).
+@rem Usage: rt [-d] [-O] [-q] regrtest_args
+@rem -d Run Debug build (python_d.exe). Else release build.
+@rem -O Run python.exe or python_d.exe (see -d) with -O.
+@rem -q "quick" -- normally the tests are run twice, the first time
+@rem after deleting all the .py[co] files reachable from Lib/.
+@rem -q runs the tests just once, and without deleting .py[co] files.
+@rem All leading instances of these switches are shifted off, and
+@rem whatever remains is passed to regrtest.py. For example,
+@rem rt -O -d -x test_thread
+@rem runs
+@rem python_d -O ../lib/test/regrtest.py -x test_thread
+@rem twice, and
+@rem rt -q -g test_binascii
+@rem runs
+@rem python_d ../lib/test/regrtest.py -g test_binascii
+@rem to generate the expected-output file for binascii quickly.
@set _exe=python
@set _qmode=no
@set _dashO=