"Data model" page is too long

Documentation

The Data model document is very long, and as a result it basically never shows up in search engine results, because 90% of the page is considered irrelevant for any query like "python __hash__".

I suggest we split it up by top-level topic, e.g. we add a dedicated page for "Special method names".

See also #126052

首先查看 docs.python.org/3/reference/datamodel.html 中的 Data model 文档以及相关 issue #126052。确定顶层主题的划分，包括一个专门的 Special method names 页面，然后更新文档结构和链接，使每个主题都能被独立发现。