update known issues (newline/linefeed/unicode)

- closes #454
- TODO: might want to autodetect semi-unicode support and fallback to ascii?

README.rst

@@ -222,9 +222,13 @@ of a neat one-line progress bar.
       `IDLE <https://github.com/tqdm/tqdm/issues/191#issuecomment-230168030>`__,
       `ConEmu <https://github.com/tqdm/tqdm/issues/254>`__ and
       `PyCharm <https://github.com/tqdm/tqdm/issues/203>`__ (also
-      `here <https://github.com/tqdm/tqdm/issues/208>`__ and
-      `here <https://github.com/tqdm/tqdm/issues/307>`__)
-      lack full support.
+      `here <https://github.com/tqdm/tqdm/issues/208>`__,
+      `here <https://github.com/tqdm/tqdm/issues/307>`__, and
+      `here <https://github.com/tqdm/tqdm/issues/454#issuecomment-335416815>`__)
+      lack full support. Windows consoles often only partially support unicode
+      and thus
+      `often require ascii=True <https://github.com/tqdm/tqdm/issues/454#issuecomment-335416815>`__
+      (also `here <https://github.com/tqdm/tqdm/issues/499>`__).
     * Windows: additionally may require the Python module ``colorama``
       to ensure nested bars stay within their respective lines.
 - Wrapping enumerated iterables: use ``enumerate(tqdm(...))`` instead of