Adding plotting specific documentation

Comment originally from @MeyerBender, thanks for the feedback!

documentation: in general, I think it would be good to have one or two notebooks that exclusively focus on visualization. Right now, it is very hard to find this in the spatialdata docs. Maybe something similar to this, which shows off the most important plotting functions in spatialproteomics.

Currently we have plotting notebooks but hidden under the "Technology-specific" section in the docs. And we have another notebook in a separate repo (=not really discoverable).

Improving the docs with a visualization-specific notebook that is easily discoverable would be valuable.

首先查看文档中 "Technology-specific" 部分下的绘图 notebooks，以及现有的 spatialdata-workshops/notebooks/nb2_static_plotting.ipynb。确定关键的绘图函数，以及文档中如何链接 notebooks。完成的标准是：在 spatialdata-plot 文档中可以轻松找到一个专注于可视化的 notebook，并且该 notebook 覆盖重要的绘图函数。