Autotest: Move the README file to the tests/auto folder

So it is more visible. Add some tips if user needs to run
the autotests.

Change-Id: I86739a06b1cd62a061aec20fb640f7c66cfc557c
Reviewed-by: Liang Qi <liang.qi@digia.com>

tests/auto/README.txt

+
+Here are some tips if you need to run the Qt Quick Controls auto tests.
+
+ - Testplugin
+
+Some autotests require the test plugin under testplugin/QtQuickControlsTests.
+
+The test plugin is not installed (i.e. to the qml folder), so
+in order for the tst_controls to find it, you can either:
+
+- Run make check in the controls folder. The plugin will be found
+at run time because IMPORTPATH is defined in the pro file.
+
+- In Qt Creator run settings or in the console, set QML2_IMPORT_PATH
+macro to the testplugin path. At run time QML2_IMPORT_PATH is used by
+by qmlscene to find imports required.
+i.e: export QML2_IMPORT_PATH=<path_qtquickcontrols_git_clone>/tests/auto/testplugin
+
+- Use the -import command-line option:
+$ cd build/qt5/qtquickcontrols/tests/auto/controls
+$ ./tst_controls -import ../testplugin
+
+ - Running specific tests:
+
+i) It is possible to run a single file using the -input option. For example:
+
+$ ./tst_controls -input data/test.qml
+
+$ ./tst_controls -input <full_path>/test.qml
+
+Specifying the full path to the qml test file is for example needed for shadow builds.
+
+
+ii) The -functions command-line option will return a list of the current tests functions.
+It is possible to run a single test function using the name of the test function as an argument. For example:
+
+tst_controls Test_Name::function1
+

tests/auto/testplugin/README.txt

-
-The test plugin is not installed (i.e. to the qml folder).
-In order for the tst_controls to find it, you can either:
-
-- Run make check in the controls folder. The plugin will be found
-at run time because IMPORTPATH is defined in the pro file.
-
-- In Qt Creator run settings or in the console, set QML2_IMPORT_PATH
-macro to the testplugin path. At run time QML2_IMPORT_PATH is used by
-by qmlscene to find imports required.
-i.e: export QML2_IMPORT_PATH=<path_qtquickcontrols_git_clone>/tests/auto/testplugin