Updated Standard Library Coverage (markdown)

Standard-Library-Coverage.md

@@ -3,7 +3,7 @@
 | [__future__](https://docs.python.org/3/library/__future__.html#module-__future__) |  Future statement definitions | ✅ | [micropython-lib](https://github.com/micropython/micropython-lib/tree/master/python-stdlib/__future__)
 | [__main__](https://docs.python.org/3/library/__main__.html#module-__main__) |  The environment where the top-level script is run. | ✅ | 
 | [_thread](https://docs.python.org/3/library/_thread.html#module-_thread) |  Low-level threading API. | ✅ | See [[Threads]] for more info. |
-| [abc](https://docs.python.org/3/library/abc.html#module-abc) |  Abstract base classes according to :pep:`3119`. | ✅ | [micropython-lib](https://github.com/micropython/micropython-lib/tree/master/python-stdlib/abc)
+| [abc](https://docs.python.org/3/library/abc.html#module-abc) |  Abstract base classes according to :pep:`3119`. | ❌ | Placeholder in [micropython-lib](https://github.com/micropython/micropython-lib/tree/master/python-stdlib/abc)
 | [argparse](https://docs.python.org/3/library/argparse.html#module-argparse) |  Command-line option and argument parsing library. | ✅ | [micropython-lib](https://github.com/micropython/micropython-lib/tree/master/python-stdlib/argparse)
 | [array](https://docs.python.org/3/library/array.html#module-array) |  Space efficient arrays of uniformly typed numeric values. | ✅ | [built-in](https://docs.micropython.org/en/latest/library/uarray.html)
 | [ast](https://docs.python.org/3/library/ast.html#module-ast) |  Abstract Syntax Tree classes and manipulation. | ❌ | Requires `_ast` to be implemented in core MicroPython.