GH-73991: Split "Directory and file operations" section in shutil docs by barneygale · Pull Request #119159 · python/cpython

…il docs

Split "Directory and file operations" section in five:

1. "Copying files"
2. "Recursively copying, moving and removing"
3. "Querying disk usage"
4. "Changing file ownership"
5. "Finding executables"

The "Platform-dependent efficient copy operations" information is moved to
"Copying files". The examples of `copytree()` and `rmtree()` are moved into
their function docs.

This should be slightly easier to navigate for users, and draws more of a
distinction between the lower-level file copying functions and the
higher-level `copytree()` / `rmtree()` / `move()` functions.