Docs: Add HelloWorld Example Notebook (#69)

[info-gallary]

Describe your changes

Added a HelloWorld.ipynb notebook to the docs folder to provide a simple, step-by-step onboarding guide.

This resolves the need for an end-to-end example notebook by demonstrating:

• Environment setup using pdm.
• Data loading and preparation with mllam-data-prep.
• Hierarchical graph generation with create_graph.py.
• CPU hi_lam training workflow.
• Evaluation metrics and plotting generation with wandb.
• Tips for scaling to GPUs and larger datasets.

(I tested the environment setup and verified that mllam-data-prep and create_graph.py
execute as expected with the provided config)

Dependencies: Added ipykernel to development dependencies to support running the notebook.

Issue Link

closes #69

Type of change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [✔️] 📖 Documentation (Addition or improvements to documentation)

Checklist before requesting a review

• [✔️] My branch is up-to-date with the target branch - if not update your fork with the changes from the target branch (use pull with --rebase option if possible).
• [✔️] I have performed a self-review of my code
• For any new/modified functions/classes I have added docstrings that clearly describe its purpose, expected inputs and returned values
• I have placed in-line comments to clarify the intent of any hard-to-understand passages of my code
• I have updated the README to cover introduced code changes
• [✔️ ] I have added tests that prove my fix is effective or that my feature works
• [✔️ ] I have given the PR a name that clearly describes the change, written in imperative form (context).
• [✔️ ] I have requested a reviewer and an assignee (assignee is responsible for merging). This applies only if you have write access to the repo, otherwise feel free to tag a maintainer to add a reviewer and assignee.

Checklist for reviewers

Each PR comes with its own improvements and flaws. The reviewer should check the following:

• the code is readable
• the code is well tested
• the code is documented (including return types and parameters)
• the code is easy to maintain

Author checklist after completed review

• [ ✔️] I have added a line to the CHANGELOG describing this change, in a section
  reflecting type of change (add section where missing):
  • added: when you have added new functionality
  • changed: when default behaviour of the code has been changed
  • fixes: when your contribution fixes a bug
  • maintenance: when your contribution is relates to repo maintenance, e.g. CI/CD or documentation

Checklist for assignee

• PR is up to date with the base branch
• the tests pass
• (if the PR is not just maintenance/bugfix) the PR is assigned to the next milestone. If it is not, propose it for a future milestone.
• author has added an entry to the changelog (and designated the change as added, changed, fixed or maintenance)
• Once the PR is ready to be merged, squash commits and merge the PR.

[sadamov]

#202 the danra hello world example is almost complete. Please add your input there