Clarify the documentation of the Pattern character classes.

Android (via icu4c) supports the full Unicode TR-18 definitions
rather than the traditional ASCII-only ones. Document this fact.

Bug: http://code.google.com/p/android/issues/detail?id=21176
Change-Id: If9b94d4e7769ec1ef7c443a7db47bc7586f49b44
2 files changed