Add example notebook for exploring mosquito species distribution

[priyarai121]

While exploring the mosquito sample metadata available through the malariagen_data API, I noticed that an example showing how to analyze mosquito species distribution could be useful for new users.

Motivation

Understanding the distribution of mosquito species is important for researchers studying malaria vectors and population structure. A simple example notebook demonstrating this analysis could help users quickly explore the dataset.

Proposed Contribution

I would like to contribute a notebook under the examples/ directory that demonstrates:

• Loading mosquito sample metadata
• Counting mosquito species present in the dataset
• Visualizing species distribution using a bar chart

Please let me know if this type of example would be helpful for the repository.