docs(cxx): add a section about std::filesystem limitations

Co-authored-by: Shen Meng Jing <shenmengjing@espressif.com>

docs/en/api-guides/cplusplus.rst

@@ -13,6 +13,7 @@ The following C++ features are supported:
 - :ref:`cplusplus_multithreading`
 - :ref:`cplusplus_rtti`
 - :doc:`thread-local-storage` (``thread_local`` keyword)
+- :ref:`cplusplus_filesystem`
 - All C++ features implemented by GCC, except for some :ref:`cplusplus_limitations`. See `GCC documentation <https://gcc.gnu.org/projects/cxx-status.html>`_ for details on features implemented by GCC.
 
 
@@ -94,6 +95,21 @@ Enabling this option compiles all C++ files with RTTI support enabled, which all
 
 See :example:`cxx/rtti` for an example of using RTTI in ESP-IDF. Specifically, this example demonstrates how to use the RTTI feature in ESP-IDF, enabling compile time support for RTTI, and showing how to print demangled type names of objects and functions, and how dynamic_cast behaves with objects of two classes derived from a common base class.
 
+.. _cplusplus_filesystem:
+
+Filesystem Library
+------------------
+
+C++ Filesystem library (``#include <filesystem>``) features are supported in ESP-IDF, with the following exceptions:
+
+- Since symbolic and hard links are not supported in ESP-IDF, related functions are not implemented.
+- ``std::filesystem::space`` is not implemented.
+- ``std::filesystem::resize_file`` is not implemented.
+- ``std::filesystem::current_path`` always returns ``/``. Setting the current path is not supported.
+- ``std::filesystem::permissions`` doesn't support setting file permissions.
+
+Note that the choice of the filesystem also affects the behavior of the filesystem library. For example, SPIFFS filesystem has limited support for directories, therefore the related std::filesystem functions may not work as they do on a filesystem which does support directories.
+
 Developing in C++
 -----------------