Add user-friendly landing page to DEA Sandbox

[robbibt]

Proposed changes

This PR provides a user friendly landing page that will make it easier for users to learn about the content available in the Sandbox, and useful reference information in the Knowledge Hub:

Closes issues (optional)

• Closes Issue DEA Sandbox landing page Jupyter notebook pointing to Knowledge Hub #1188

Checklist

(Replace [ ] with [x] to check off)

• Notebook created using the DEA-notebooks template
• Remove any unused Python packages from Load packages
• Remove any unused/empty code cells
• Remove any guidance cells (e.g. General advice)
• Ensure that all code cells follow the PEP8 standard for code. The jupyterlab_code_formatter tool can be used to format code cells to a consistent style: select each code cell, then click Edit and then one of the Apply X Formatter options (YAPF or Black are recommended).
• Include relevant tags in the final notebook cell (refer to the DEA Tags Index, and re-use tags if possible)
• Clear all outputs, run notebook from start to finish, and save the notebook in the state where all cells have been sequentially evaluated
• Test notebook on both the NCI and DEA Sandbox (flag if not working as part of PR and ask for help to solve if needed)
• If applicable, update the Notebook currently compatible with the NCI|DEA Sandbox environment only line below the notebook title to reflect the environments the notebook is compatible with
• Check for any spelling mistakes using the DEA Sandbox's built-in spellchecker (double click on markdown cells then right-click on pink highlighted words). For example:

[review-notebook-app]

Check out this pull request on 

See visual diffs & provide feedback on Jupyter Notebooks.

---

Powered by ReviewNB

[geoscience-aman]

Looks nice!

[geoscience-aman]

Suggest <img src="Supplementary_data/dea_logo_wide.jpg" width="2000"/> maybe so it covers the whole width of a larger monitor screen without affecting the display on a smaller laptop screen?

[geoscience-aman]

When referring to DEA Tools, maybe we can link to the PyPI package?
https://pypi.org/project/dea-tools/0.3.0/

[benji-glitsos-ga]

Hi @geoscience-aman , I think it would be better if the header image was wider but I tried applying a larger width and it stretches the image beyond its natural limit and makes it blurry unfortunately. Unless we have a larger version of dea_logo_wide.jpg somewhere @robbibt ?

Also, it will be great if we link to the Pypy package however I think it would be better for the user experience if we put it on the DEA Tools cover page: https://docs.dea.ga.gov.au/notebooks/Tools/

I will create a PR to suggest adding it to that page.

[robbibt]

Yeah, I reckon we add a PyPI link somewhere here, so it's easily accessible to users accessing the Python API docs:

[robbibt]

I agree 💯 about the banner, but as far as I know it's the widest version we have... although I can't remember where it originally came from or if it was something custom we put together for DEA Notebooks.

Might need to be a future improvement for this one I think

[BexDunn]

I'm so excited about this :) Looks good