Add FITS imputation model and update docs #479

	name: Auto reply to new issues and PR

	on:
	issues:
	types: [opened]
	pull_request:
	branches: [main, dev]
	types: [opened]

	jobs:
	greeting:
	runs-on: ubuntu-latest

	permissions:
	pull-requests: write
	issues: write

	steps:
	- uses: actions/first-interaction@v1
	with:
	repo-token: ${{ secrets.GITHUB_TOKEN }}
	issue-message: \|
	Hi there 👋,

	Thank you so much for your attention to PyPOTS! You can [follow me](https://github.com/WenjieDu) on GitHub
	to receive the latest news of PyPOTS. If you find PyPOTS helpful to your work, please star⭐️ this repository.
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	It matters and is definitely a kind of contribution to the community.

	I have received your message and will respond ASAP. Thank you for your patience! 😃

	Best,
	Wenjie
	pr-message: \|
	Hi there 👋,

	We really appreciate that you have taken the time to make this PR on PyPOTS!

	If you are trying to fix a bug, please reference the issue number in the description or give your details about the bug.
	If you are implementing a feature request, please check with the maintainers that the feature will be accepted first.

	Best,
	Wenjie

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