PathLike objects are added in 3.6 and they are mentioned in the documentation. But in some os module functions' docstrings, acceptable types of path parameter are mentioned and they are not altered to mention path-like object. For example:

chown(path, uid, gid, *, dir_fd=None, follow_symlinks=True)
    Change the owner and group id of path to the numeric uid and gid.\
    
      path
        Path to be examined; can be string, bytes, or open-file-descriptor int.

I see that path-like objects are indeed mentioned in the documentation (Doc/library/os.rst), simply stating "Changed in version 3.6: Supports a path-like object." Other methods, such as os.chroot, also mention such a change.

Comparing the docs mentioned above to the docstrings in Modules/clinic/posixmodule.c.h (and Modules/clinic/posixmodule.c for that matter), there's a clear disparity between the detail in the docs vs brevity in the docstrings (specifically in reference to os.chroot). 

Therefore, my question is: how detailed should the docstrings be and how closely should they match Doc/library/os.rst? I can certainly update the docstrings accordingly.

I don't mean to sync the docstring and the documentation totally. But just like os.chown, there are some functions explicitly mention the acceptable types of path parameter in their docstrings. I think since they already mention the types, then make the list complete. For example, I think for os.chown make the list "can be string, bytes, path-like object or open-file-descriptor int" is enough.

Hey I would like to make this change which file should I look into?

This is now carried forward in 3.8 also. Is anyone working on this issue ?
It needs to be corrected in doc-string for all method where its applicable

Farhaan Bukhsh: you said you wanted to work on this but that was over a month ago, so I presume you've directed your attention elsewhere, and I'd like to give this a try.

New changeset b942707fc23454a998323c17e30be78ff1a4f0e7 by Pablo Galindo (BNMetrics) in branch 'master':
bpo-29341: Clarify that path-like objects are accepted in some os methods (GH-10101)
https://github.com/python/cpython/commit/b942707fc23454a998323c17e30be78ff1a4f0e7

New changeset 8d2f88fb17468642813108977bb9ec5f7a065b84 by Pablo Galindo (BNMetrics) in branch '3.6':
[3.6]bpo-29341: Backport b942707 3.6 (GH-10299)
https://github.com/python/cpython/commit/8d2f88fb17468642813108977bb9ec5f7a065b84

New changeset 08026b103ea8f4c9f2b5045ef7806dd8b760da2b by Pablo Galindo (BNMetrics) in branch '3.7':
[3.7]bpo-29341: Backport b942707 3.7 (#10298)
https://github.com/python/cpython/commit/08026b103ea8f4c9f2b5045ef7806dd8b760da2b

The docstrings are fixed and the (manual!) backports to 3.7 and 3.6 are done. Very good job, Luna!