Setup document build system with Sphinx

[gigony]

• Add initial document setup with Sphinx
• Initial code update to fix Sphinx build error
• Update run script - gen_docs/gen_docs_dev command

Building the documentation

MONAI's documentation is located at docs/.

./run gen_docs  # '-h' for help

The above command builds HTML documents in the dist/docs folder, they are used to automatically generate documents in https://docs.monai.io.

To test HTML docs locally with development server, execute below command:

./run gen_docs_dev  # '-h' for help

The above command launches a live server to build docs in runtime.

Before submitting a pull request, it is recommended to:

• edit the relevant .md files in docs/source accordingly.
  • The MyST Syntax Guide
  • Optional MyST Syntaxes
  • MyST Syntax Reference
  • MyST with Sphinx
• check the auto-generated documentation (by browsing the generated documents after executing ./run gen_docs_dev)
• build HTML documentation locally (./run gen_docs)
• execute ./run gen_docs_dev to clean temporary and final documents.

closes #34

[MMelQin]

Approved with a comment

[MMelQin]

A reference to the Triton doc would help.

[gigony]

Oh, Thank you! Will update in other PR when docstring is updated.