MAINTAINERS: update f2fs entry

This patch includes below modifications:
1. change my maintainership from reviewer to maintainer.
2. remove maintainership of Changman Lee since he is not active about
one and a half year.
3. change website of f2fs from wiki to kernel one.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

MAINTAINERS

@@ -5060,10 +5060,9 @@ F:	include/linux/fscrypto.h
 
 F2FS FILE SYSTEM
 M:	Jaegeuk Kim <jaegeuk@kernel.org>
-M:	Changman Lee <cm224.lee@samsung.com>
-R:	Chao Yu <yuchao0@huawei.com>
+M:	Chao Yu <yuchao0@huawei.com>
 L:	linux-f2fs-devel@lists.sourceforge.net
-W:	http://en.wikipedia.org/wiki/F2FS
+W:	https://f2fs.wiki.kernel.org/
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git
 S:	Maintained
 F:	Documentation/filesystems/f2fs.txt