Refactor docs about contributions to CONTRIBUTING.md.

Per the review comments.

googletest/README.md

@@ -358,38 +358,3 @@ instead of
     TEST(SomeTest, DoesThis) { ... }
 
 in order to define a test.
-
-## Developing Google Test ##
-
-This section discusses how to make your own changes to Google Test.
-
-### Testing Google Test Itself ###
-
-To make sure your changes work as intended and don't break existing
-functionality, you'll want to compile and run Google Test's own tests.
-For that you can use CMake:
-
-    mkdir mybuild
-    cd mybuild
-    cmake -Dgtest_build_tests=ON ${GTEST_DIR}
-
-Make sure you have Python installed, as some of Google Test's tests
-are written in Python.  If the cmake command complains about not being
-able to find Python (`Could NOT find PythonInterp (missing:
-PYTHON_EXECUTABLE)`), try telling it explicitly where your Python
-executable can be found:
-
-    cmake -DPYTHON_EXECUTABLE=path/to/python -Dgtest_build_tests=ON ${GTEST_DIR}
-
-Next, you can build Google Test and all of its own tests.  On \*nix,
-this is usually done by 'make'.  To run the tests, do
-
-    make test
-
-All tests should pass.
-
-Normally you don't need to worry about regenerating the source files,
-unless you need to modify them.  In that case, you should modify the
-corresponding .pump files instead and run the pump.py Python script to
-regenerate them.  You can find pump.py in the [scripts/](scripts/) directory.
-Read the [Pump manual](docs/PumpManual.md) for how to use it.