[examples] Add notes on how to run the simple-make examples.

examples/simple-make/README.txt

@@ -13,31 +13,73 @@ distinction between ``Rules`` and ``Tasks`` for simplicity. ``llbuild`` is
 currently designed with the expectation that most clients will have some similar
 kind of framework.
 
+
+Installing
+==========
+
+To run these examples, you will need:
+
+1. A built copy of ``llbuild.dylib`` in
+   ``${LLBUILD}/build/lib/libllbuild.dylib`` (the default location if you use a
+   CMake/Ninja build in a ``build`` subdirectory of the project).
+
+2. The ``cffi`` Python module available.
+
+3. The ``llbuild`` Python module available.
+
+The easiest way to accomplish this is with::
+
+  # Configure and build ``llbuild`` in the expected location.
+  cd path/to/llbuild
+  mkdir -p build
+  cd build
+  cmake -G Ninja ..
+  ninja
+
+  # Install virtualenv, if not present.
+  sudo easy_install virtualenv
+
+  # Create a virtualenv and install ``cffi`` into it.
+  #
+  # We set CFLAGS to work around CFFI not properly getting the right include
+  # paths if there is no root SDK.
+  cd path/to/llbuild/examples/simple-make
+  virtualenv venv
+  env CFLAGS="-I$(xcrun --show-sdk-path)/usr/include/ffi" venv/bin/pip install cffi
+  source venv/bin/activate
+
+  # Ensure Python can find the ``llbuild`` module.
+  export PYTHONPATH=path/to/llbuild/bindings/python
+
+
+Examples
+========
+
 The specific examples are:
 
-1. ``count-lines-1``
+1. ``count-lines-1 <FILE_PATH>``
 
    This is a minimal demonstration of the ``simplebuild`` framework that counts
    the number of lines of an input file path.
 
-2. ``count-lines-2``
+2. ``count-lines-2 <FILE_PATH>``
 
    This is an extension of ``count-lines-1`` that adds external-synchronization
    on the file system state of the input, so that we can persist the count in a
    database.
 
-3. ``count-lines-3``
+3. ``count-lines-3 <DIR_PATH>``
 
    This is an extension of ``count-lines-2`` that shows how to count the lines
    for all files in a directory with appropriate dependencies so that the count
    is recomputed when the directory or the files change.
 
-4. ``count-lines-4``
+4. ``count-lines-4 <DIR_PATH>``
 
    This is an extension of ``count-lines-3`` that shows how we would deal with
    counting the lines using an external tool.
 
-5. ``simple-make``
+5. ``simple-make <DIR_PATH>``
 
    This is an extension of the above examples to build all of the source files
    in a directory into an executable. It handles automatically rebuilding when