[SYCLomatic][DOC] Add README for docs (#804)

Add README with info re set up to build docs locally.
Update conf.py to remove un-used extension.

Signed-off-by: Kristal Dale <[email protected]>

Author: krisdale

docs/README.md

@@ -0,0 +1,37 @@
+# Documentation Build Instructions
+
+SYCLomatic documentation is written using [reStructuredText](http://www.sphinx-doc.org/en/master/usage/restructuredtext/basics.html) and built using [Sphinx](http://sphinx-doc.org/). Follow the instructions in this README to build the documentation locally.
+
+## Requirements
+
+The following must be installed to build the documentation:
+
+- Python 3
+- Sphinx
+- Theme: sphinx_book_theme
+
+## Contribute to the Documentation
+
+Please make yourself familiar with the SYCLomatic [contribution guidelines](https://github.com/oneapi-src/SYCLomatic/blob/SYCLomatic/CONTRIBUTING.md) before submitting a contribution.
+
+For documentation contributions in particular: 
+
+- The [DOC] tag should be present in the commit message title. 
+- Contributions should be tested (build with no errors) before submitting a PR.
+- PRs should be granular and purpose specific: One PR should contain one unit of change. 
+- Submit content changes separate from formatting changes. 
+
+## Build the Documentation
+
+You can build the documentation locally to preview your changes and make sure there are no errors. In the `docs` directory of your local SYCLomatic repository run:
+
+	make html
+
+The generated HTML will be located in `docs/_build/html`.
+
+When testing changes in the documentation, make sure to remove the previous build before building again. To do this run:
+
+	make clean
+
+
+

docs/conf.py

@@ -31,7 +31,7 @@
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
-extensions = ['sphinx2dita']
+extensions = []
 
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']