Readme Install Instructions Update (#426)

* Updated README build from source section so it is easier to follow
* Adjusted installation comments a little bit to better fit the GitHub markdown section

Author: TwistedTwigleg

README.md

@@ -27,45 +27,67 @@ __Jump To:__
 
 ### Minimum Requirements
 * C++ 11 or higher
+    * Clang 3.9+ or GCC 4.8+ or MSVC 2015+
 * CMake 3.1+
-* Clang 3.9+ or GCC 4.8+ or MSVC 2015+
 
 [Step-by-step instructions](./PREREQUISITES.md)
 
 
 ### Build from source
 
-#### Automatically Build and Install AWS Dependencies
-
-Note: `-DCMAKE_INSTALL_PREFIX` can be any path where the project needs to be installed. Taking sdk-cpp-workspace as an example here.
-
 #### MacOS and Linux
 
 ``` sh
-mkdir sdk-cpp-workspace
-cd sdk-cpp-workspace
+# Create a workspace directory to hold all the SDK files
+mkdir sdk-workspace
+cd sdk-workspace
+# Clone the repository
 git clone --recursive https://github.com/aws/aws-iot-device-sdk-cpp-v2.git
+# Ensure all submodules are properly updated
+cd aws-iot-device-sdk-cpp-v2
+git submodule update --init --recursive
+cd ..
+# Make a build directory for the SDK. Can use any name.
+# If working with multiple SDKs, using a SDK-specific name is helpful.
 mkdir aws-iot-device-sdk-cpp-v2-build
 cd aws-iot-device-sdk-cpp-v2-build
-cmake -DCMAKE_INSTALL_PREFIX="<absolute path sdk-cpp-workspace dir>" -DCMAKE_BUILD_TYPE="<Release|RelWithDebInfo|Debug>" ../aws-iot-device-sdk-cpp-v2
+# Generate the SDK build files.
+# -DCMAKE_INSTALL_PREFIX needs to be the absolute/full path to the directory.
+#     (Example: "/Users/example/sdk-workspace/).
+# -DCMAKE_BUILD_TYPE can be "Release", "RelWithDebInfo", or "Debug"
+cmake -DCMAKE_INSTALL_PREFIX="<absolute path to sdk-workspace>" -DCMAKE_BUILD_TYPE="Debug" ../aws-iot-device-sdk-cpp-v2
+# Build and install the library. Once installed, you can develop with the SDK and run the samples
 cmake --build . --target install
 ```
 
 #### Windows
 
 ``` sh
-mkdir sdk-cpp-workspace
+# Create a workspace directory to hold all the SDK files
+mkdir sdk-workspace
 cd sdk-cpp-workspace
+# Clone the repository
 git clone --recursive https://github.com/aws/aws-iot-device-sdk-cpp-v2.git
+# Ensure all submodules are properly updated
+cd aws-iot-device-sdk-cpp-v2
+git submodule update --init --recursive
+cd ..
+# Make a build directory for the SDK. Can use any name.
+# If working with multiple SDKs, using a SDK-specific name is helpful.
 mkdir aws-iot-device-sdk-cpp-v2-build
 cd aws-iot-device-sdk-cpp-v2-build
+# Generate the SDK build files.
+# -DCMAKE_INSTALL_PREFIX needs to be the absolute/full path to the directory.
+#     (Example: "C:/users/example/sdk-workspace/).
 cmake -DCMAKE_INSTALL_PREFIX="<absolute path sdk-cpp-workspace dir>" ../aws-iot-device-sdk-cpp-v2
-cmake --build . --target install --config "<Release|RelWithDebInfo|Debug>"
+# Build and install the library. Once installed, you can develop with the SDK and run the samples
+# -config can be "Release", "RelWithDebInfo", or "Debug"
+cmake --build . --target install --config "Debug"
 ```
 
-Due to maximum path length limitations in the Windows API, we recommend cloning to a short path like: `C:\dev\iotsdk`
-
-`--config` is only REQUIRED for multi-configuration build tools (VisualStudio/MsBuild being the most common).
+**Windows specific notes**:
+* Due to maximum path length limitations in the Windows API, we recommend cloning to a short path like: `C:\dev\iotsdk`
+* `--config` is only REQUIRED for multi-configuration build tools (VisualStudio/MsBuild being the most common).
 
 ## Samples