Write README.md for crates/mohu-dtype

[Bbn08]

Summary

crates/mohu-dtype has no README.md. This crate defines the DType enum used by every other mohu crate and deserves clear standalone documentation.

What to do

Create crates/mohu-dtype/README.md covering:

• One-paragraph description.
• The full dtype table (variant, Rust type, bytes, alignment) -- already in dtype.rs as a doc comment, copy it here.
• A code example showing DType::from_str, itemsize, is_float, promote, and can_cast.
• A section on the Scalar trait and which Rust types implement it.
• A section on DLPack dtype code mapping.
• Link to workspace CONTRIBUTING.md.

Acceptance criteria

• crates/mohu-dtype/README.md exists.
• Code examples compile.
• Dtype table is accurate and matches DType::itemsize() values.

Signed-off-by: Bbn08 atrancendentbeing@gmail.com

[shravanithouta108]

/assign gssoc

[Arya-ch26]

/assign

[github-actions]

Assigned to @Arya-ch26 ✓

[vishakhaojha57]

Hi! I'm a GSSoC 2026 contributor and I'd love to work on this issue. I've already set up the repo locally and gone through the contributing guide. Can I be assigned?

[nirmanshandilya]

/assign

[github-actions]

Assigned to @nirmanshandilya ✓