* Setup documentation server, move doc files from /doc to /docs as per Github Pages convention.
* Include deleted files in patch.
* /doc -> /docs
* /doc -> /docs
* Update documentation on importing ONNX spec into ONNX Dialect; provide documentation on how to add new documentation pages.
* Generate ONNX Dialect TableGen Inc files & operation importing inc files when necessary.
* Ensure TableGen inc file is generated before TableGen is invoked.
* Nit: capitalize builder -> Builder.
* Use file-same-as-stdout directive to ensure generated files are always up-to-date in our codebase.
* Use more up-to-date version of ONNXOps.td.inc.
* Do not automatically invoke gen_doc.py.
* Support dry run in gen_doc.py.
* Fix case.
* Remove debug code.
* Add test for new doc_check primitive.
* Add documentation for file-same-as-stdout.
* Provide more comments.
* Add DocCheck to DocCheck README.
* Nit: format CMake script.
* Update comments.
Co-authored-by: Alexandre Eichenberger <alexe@us.ibm.com>