adding initial files for sphinx documentation

Just added the files and directories that would be used for making Sphinx documentation.
More needs to be added, especially in the future, but this is an important start.
I didn't include the output of a build as it generates a log of "junk" that we might not want, since we can just generate it when we need it.
* Why is this .txt instead of .rst?
* Convention usually uses feature_list.rst for filenames, versus TitleCase