Documentation: kunit: Remove references to --defconfig

The --defconfig option in kunit_tool was removed in [1], but the getting
started and kunit_tool documentation still encouraged its use. Update
those documents to reflect that it's no-longer required, and is the
default behaviour if no .kunitconfig is found.

Also update a couple of places where .kunitconfig is still referred to
as kunitconfig (this was changed in [2]).

[1]:
https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git/commit/?h=kunit-fixes&id=9bdf64b35117cc10813d24e1842cd8ee40ecbf19
[2]:
https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git/commit/?h=kunit-fixes&id=14ee5cfd4512ee3d1e0047d8751450dcc6544070

Signed-off-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Documentation/dev-tools/kunit/kunit-tool.rst

@@ -19,13 +19,13 @@ compiles the kernel as a standalone Linux executable that can be run like any
 other program directly inside of a host operating system. To be clear, it does
 not require any virtualization support: it is just a regular program.
 
-What is a kunitconfig?
-======================
+What is a .kunitconfig?
+=======================
 
 It's just a defconfig that kunit_tool looks for in the base directory.
 kunit_tool uses it to generate a .config as you might expect. In addition, it
 verifies that the generated .config contains the CONFIG options in the
-kunitconfig; the reason it does this is so that it is easy to be sure that a
+.kunitconfig; the reason it does this is so that it is easy to be sure that a
 CONFIG that enables a test actually ends up in the .config.
 
 How do I use kunit_tool?
@@ -46,16 +46,9 @@ However, you most likely want to use it with the following options:
 - ``--timeout`` sets a maximum amount of time to allow tests to run.
 - ``--jobs`` sets the number of threads to use to build the kernel.
 
-If you just want to use the defconfig that ships with the kernel, you can
-append the ``--defconfig`` flag as well:
-
-.. code-block:: bash
-
-	./tools/testing/kunit/kunit.py run --timeout=30 --jobs=`nproc --all` --defconfig
-
 .. note::
-	This command is particularly helpful for getting started because it
-	just works. No kunitconfig needs to be present.
+	This command will work even without a .kunitconfig file: if no
+        .kunitconfig is present, a default one will be used instead.
 
 For a list of all the flags supported by kunit_tool, you can run:
 

Documentation/dev-tools/kunit/start.rst

@@ -18,7 +18,7 @@ The wrapper can be run with:
 
 .. code-block:: bash
 
-	./tools/testing/kunit/kunit.py run --defconfig
+	./tools/testing/kunit/kunit.py run
 
 For more information on this wrapper (also called kunit_tool) check out the
 :doc:`kunit-tool` page.