"Built-in Types" page is too long

Documentation

The Built-in Types 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 strings".

I suggest we split it up by top-level topic, e.g. we add a dedicated page for "Text Sequence Type — str"

See also #126053

首先查看 issue 中链接的 Built-in Types 页面以及 #126053 中的相关讨论。确定应成为独立页面的顶层主题，包括拟议的 Text Sequence Type — str 页面。完成的标准是：文档被拆分为有用的主题页面，同时不丢失现有的内置类型覆盖范围。