Update README

Author: gjbex

README.md

@@ -11,6 +11,11 @@ For information on the training, see the website
    presentation used for the training.
 1. [`source-code`](source-code): directory that contains sample code written to
    develop the slides and illustrate concepts.
+1. [`environment.yml`](environment.yml): conda environment file intended to be
+   cross-platform.
+1. [`python_for_data_science_linux64_conda_specs.txt`](python_for_data_science_linux64_conda_specs.txt):
+   conda environment specification file specific for 64-bit Linux to precisely
+   reproduce the environment on which the code was developed.
 1. [License](LICENSE): license information for the material in this repository.
 1. [Contributing](CONTRIBUTING.md): information on how to contribute to this
    repository.