The documentation is split across two subfolders, source and assets. The folder source contains the static source files that make up the user guide, which are mostly markdown files and the snippets of code. The folder assets contains (dynamically generated) assets used by those files, including data files for the snippets and images with plots or diagrams.

Do not merge the two folders together. In PR #18773 we introduced this split to fix the MkDocs server live reloading. If everything is in one folder docs, the MkDocs server will watch the folder docs. When you make one change the MkDocs server live reloads and rebuilds the docs. This triggers scripts that build asset files, which change the folder docs, leading to an infinite reloading loop.