MAINTAINERS: erofs: add EROFS webpage

Add a new `W:` field of the EROFS entry points to the documentation
site at <https://erofs.docs.kernel.org>.

In addition, update the in-tree documentation and Kconfig too.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20231117085329.1624223-1-hsiangkao@linux.alibaba.com

Author: hsiangkao

Documentation/filesystems/erofs.rst

@@ -91,6 +91,10 @@ compatibility checking tool (fsck.erofs), and a debugging tool (dump.erofs):
 
 - git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs-utils.git
 
+For more information, please also refer to the documentation site:
+
+- https://erofs.docs.kernel.org
+
 Bugs and patches are welcome, please kindly help us and send to the following
 linux-erofs mailing list:
 

MAINTAINERS

@@ -7855,6 +7855,7 @@ R:	Yue Hu <huyue2@coolpad.com>
 R:	Jeffle Xu <jefflexu@linux.alibaba.com>
 L:	linux-erofs@lists.ozlabs.org
 S:	Maintained
+W:	https://erofs.docs.kernel.org
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs.git
 F:	Documentation/ABI/testing/sysfs-fs-erofs
 F:	Documentation/filesystems/erofs.rst

fs/erofs/Kconfig

@@ -21,7 +21,7 @@ config EROFS_FS
 	  performance under extremely memory pressure without extra cost.
 
 	  See the documentation at <file:Documentation/filesystems/erofs.rst>
-	  for more details.
+	  and the web pages at <https://erofs.docs.kernel.org> for more details.
 
 	  If unsure, say N.