788 cluser doc

[Zhiyuan-w]

Description

Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. List any dependencies that are required for this change.

Fixes #788

Type of change

What types of changes does your code introduce to DeepReg?

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• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] Code style update (formatting, renaming)
• [ ] Refactoring (no functional changes, no api changes)
• [ v] Documentation Update (fix or improvement on the documentation)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Other (if none of the other choices apply)

Checklist

Please check the boxes that apply after submitting the pull request.

If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code.

• [ v] I have installed pre-commit using pre-commit install and formatted all changed files. If you are not certain, run pre-commit run --all-files.
• [v ] My commits' message styles matches our requested structure, e.g. Issue #<issue number>: detailed message.
• [ ] I have updated the change log file regarding my changes.
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ v] I have added necessary documentation (if appropriate)