include Section about building tf from source in README

Author: sjentzsch

README.md

@@ -101,6 +101,116 @@ For GPU-accelerated tensorflow, ensure you do or have done the following:
 
    Ansible will immediately ask you for your sudo password, as packages etc. will need to be installed through root user.
 
+# Build TensorFlow from Source
+
+> Note: As of now, if you configured to build TensorFlow from Source, you need to follow this guide after running the Ansible playbook. In the future, this should mostly be handled by Ansible.
+
+Inside `ml/tensorflow` (default location) run `./configure`.
+
+Here is my sample dialogue and the answers I gave to the questions: 
+
+> Note: Ensure to refer to the proper Python version you want to use! Here I compiled with Python 3.5.
+
+```
+Extracting Bazel installation...
+You have bazel 0.7.0 installed.
+Please specify the location of python. [Default is /usr/bin/python]: /usr/bin/python3
+
+
+Found possible Python library paths:
+  /usr/local/lib/python3.5/dist-packages
+  /usr/lib/python3/dist-packages
+Please input the desired Python library path to use.  Default is [/usr/local/lib/python3.5/dist-packages]
+
+Do you wish to build TensorFlow with jemalloc as malloc support? [Y/n]: 
+jemalloc as malloc support will be enabled for TensorFlow.
+
+Do you wish to build TensorFlow with Google Cloud Platform support? [Y/n]: n
+No Google Cloud Platform support will be enabled for TensorFlow.
+
+Do you wish to build TensorFlow with Hadoop File System support? [Y/n]: n
+No Hadoop File System support will be enabled for TensorFlow.
+
+Do you wish to build TensorFlow with Amazon S3 File System support? [Y/n]: n
+No Amazon S3 File System support will be enabled for TensorFlow.
+
+Do you wish to build TensorFlow with XLA JIT support? [y/N]: n
+No XLA JIT support will be enabled for TensorFlow.
+
+Do you wish to build TensorFlow with GDR support? [y/N]: n
+No GDR support will be enabled for TensorFlow.
+
+Do you wish to build TensorFlow with VERBS support? [y/N]: n
+No VERBS support will be enabled for TensorFlow.
+
+Do you wish to build TensorFlow with OpenCL support? [y/N]: n
+No OpenCL support will be enabled for TensorFlow.
+
+Do you wish to build TensorFlow with CUDA support? [y/N]: y
+CUDA support will be enabled for TensorFlow.
+
+Please specify the CUDA SDK version you want to use, e.g. 7.0. [Leave empty to default to CUDA 8.0]: 9.0
+
+
+Please specify the location where CUDA 9.0 toolkit is installed. Refer to README.md for more details. [Default is /usr/local/cuda]: 
+
+
+Please specify the cuDNN version you want to use. [Leave empty to default to cuDNN 6.0]: 7
+
+
+Please specify the location where cuDNN 7 library is installed. Refer to README.md for more details. [Default is /usr/local/cuda]:/usr/lib/x86_64-linux-gnu
+
+
+Please specify a list of comma-separated Cuda compute capabilities you want to build with.
+You can find the compute capability of your device at: https://developer.nvidia.com/cuda-gpus.
+Please note that each additional compute capability significantly increases your build time and binary size. [Default is: 5.0]5.0
+
+
+Do you want to use clang as CUDA compiler? [y/N]: n
+nvcc will be used as CUDA compiler.
+
+Please specify which gcc should be used by nvcc as the host compiler. [Default is /usr/bin/gcc]: 
+
+
+Do you wish to build TensorFlow with MPI support? [y/N]: n
+No MPI support will be enabled for TensorFlow.
+
+Please specify optimization flags to use during compilation when bazel option "--config=opt" is specified [Default is -march=native]: 
+
+
+Add "--config=mkl" to your bazel command to build with MKL support.
+Please note that MKL on MacOS or windows is still not supported.
+If you would like to use a local MKL instead of downloading, please set the environment variable "TF_MKL_ROOT" every time before build.
+Configuration finished
+```
+
+Then trigger the building procedure (takes about 23 minutes for me):
+
+```
+bazel build --config=opt --config=cuda //tensorflow/tools/pip_package:build_pip_package
+```
+
+Next create the package:
+
+```
+bazel-bin/tensorflow/tools/pip_package/build_pip_package /tmp/tensorflow_pkg
+```
+
+Finally install the package (choose proper pip version again! .whl-file can be named differently, investigate the folder!):
+
+```
+sudo pip3 install /tmp/tensorflow_pkg/tensorflow-1.4.0-cp35-cp35m-linux_x86_64.whl
+```
+
+See also: https://www.tensorflow.org/install/install_sources
+
+In case you want to remove previous builds again (choose proper pip version again!):
+
+```
+sudo pip3 uninstall tensorflow
+sudo pip3 uninstall tensorflow-tensorboard
+```
+
 # Run
 
 1. Inside `ml/tf_vision/config/` the YAML file `config.obj_detect.sample.yml` contains the default configuration to run.