docs: filesystems: convert dnotify.txt to ReST

- Add a SPDX header;
- Add a document title;
- Some whitespace fixes and new line breaks;
- Add table markups;
- Add it to filesystems/index.rst

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Acked-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/b39d6430d1c28438e833f01cb4597eff78703c75.1588021877.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/filesystems/dnotify.rst

@@ -1,5 +1,8 @@
-		Linux Directory Notification
-		============================
+.. SPDX-License-Identifier: GPL-2.0
+
+============================
+Linux Directory Notification
+============================
 
 	   Stephen Rothwell <sfr@canb.auug.org.au>
 
@@ -12,6 +15,7 @@ being delivered using signals.
 The application decides which "events" it wants to be notified about.
 The currently defined events are:
 
+	=========	=====================================================
 	DN_ACCESS	A file in the directory was accessed (read)
 	DN_MODIFY	A file in the directory was modified (write,truncate)
 	DN_CREATE	A file was created in the directory
@@ -19,6 +23,7 @@ The currently defined events are:
 	DN_RENAME	A file in the directory was renamed
 	DN_ATTRIB	A file in the directory had its attributes
 			changed (chmod,chown)
+	=========	=====================================================
 
 Usually, the application must reregister after each notification, but
 if DN_MULTISHOT is or'ed with the event mask, then the registration will
@@ -36,7 +41,7 @@ especially important if DN_MULTISHOT is specified.  Note that SIGRTMIN
 is often blocked, so it is better to use (at least) SIGRTMIN + 1.
 
 Implementation expectations (features and bugs :-))
----------------------------
+---------------------------------------------------
 
 The notification should work for any local access to files even if the
 actual file system is on a remote server.  This implies that remote

Documentation/filesystems/index.rst

@@ -25,6 +25,7 @@ algorithms work.
    locking
    directory-locking
    devpts
+   dnotify
 
    automount-support
 

MAINTAINERS

@@ -4996,7 +4996,7 @@ M:	Jan Kara <jack@suse.cz>
 R:	Amir Goldstein <amir73il@gmail.com>
 L:	linux-fsdevel@vger.kernel.org
 S:	Maintained
-F:	Documentation/filesystems/dnotify.txt
+F:	Documentation/filesystems/dnotify.rst
 F:	fs/notify/dnotify/
 F:	include/linux/dnotify.h