docs/library/platform: Add docs for the platform library.

Signed-off-by: Francis Dela Cruz <rainyworlds1@outlook.com>

docs/library/index.rst

@@ -71,6 +71,7 @@ library.
    json.rst
    math.rst
    os.rst
+   platform.rst
    random.rst
    re.rst
    select.rst

docs/library/platform.rst

@@ -0,0 +1,38 @@
+:mod:`platform` -- access to underlying platform’s identifying data
+===================================================================
+
+.. module:: platform
+   :synopsis: access to underlying platform’s identifying data
+
+|see_cpython_module| :mod:`python:platform`.
+
+This module tries to retrieve as much platform-identifying data as possible. It
+makes this information available via function APIs.
+
+Functions
+---------
+
+.. function:: platform()
+
+   Returns a string identifying the underlying platform. This string is composed
+   of several substrings in the following order, delimited by dashes (``-``):
+
+   - the name of the platform system (e.g. Unix, Windows or MicroPython)
+   - the MicroPython version
+   - the architecture of the platform
+   - the version of the underlying platform
+   - the concatenation of the name of the libc that MicroPython is linked to
+     and its corresponding version.
+
+   For example, this could be
+   ``"MicroPython-1.20.0-xtensa-IDFv4.2.4-with-newlib3.0.0"``.
+
+.. function:: python_compiler()
+
+   Returns a string identifying the compiler used for compiling MicroPython.
+
+.. function:: libc_ver()
+
+   Returns a tuple of strings *(lib, version)*, where *lib* is the name of the
+   libc that MicroPython is linked to, and *version* the corresponding version
+   of this libc.