docs: Fix formatting issues in weightconverter.md

[ArjunSrivastava1]

There were misalignment issues in the first diagram, patched now

Motivation to fix? well, it was misaligned, and now its not, the diagrams look better and it flows a whole lot cleaner without distracting, minor polish work

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• I confirm that this is not a pure code agent PR.

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you read the contributor guideline,
  Pull Request section?
• Was this discussed/approved via a Github issue or the forum? Please add a link
  to it if that's the case.
• no, its a minor issue i found myself while diagnosing another issue for Deepseek and Gemma models, very simple fix too
• Did you make sure to update the documentation with your changes? Here are the
  documentation guidelines, and
  here are tips on formatting docstrings.
• Did you write any new necessary tests?
• Not necessary for this

Who can review?

Not even sure whom to get a hold of for docs these days, but @stevhliu, can you make sure that it doesnt run into troubles via bot tests and stuff?

[Rocketknight1]

cc @stevhliu

[stevhliu]

thanks for the fix!

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.