fanotify.7: Add some subheadings to structure the DESCRIPTION

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man7/fanotify.7

@@ -49,7 +49,7 @@ The following system calls are used with this API:
 .BR write (2),
 and
 .BR close (2).
-.PP
+.SS fanotify_init() and notification groups
 The
 .BR fanotify_init (2)
 system call creates and initializes an fanotify notification group
@@ -101,13 +101,13 @@ access is granted or not.
 When all file descriptors referring to the fanotify notification group are
 closed, the fanotify group is released and its resources are freed for reuse by
 the kernel.
-.PP
+.SS fanotify_mark()
 The 
 .BR fanotify_mark (2)
 system call adds a file, directory, or mount to the group
 and specifies which events
 shall be reported (or ignored), or removes or modifies such an entry.
-.PP
+.SS Events, the event queue, and reading events
 When an fanotify event occurs, the fanotify file descriptor indicates as
 readable when passed to
 .BR epoll (7),
@@ -286,7 +286,7 @@ to the next metadata structure using the length indicated in the
 field of the metadata structure and reduces the remaining length of the
 buffer
 .IR len .
-.PP
+.SS Dealing with permission events
 For permission events, the application must
 .BR write (2)
 a structure of the following form to the
@@ -318,7 +318,7 @@ to deny the file operation.
 If access has been denied, the requesting application call will receive an
 error
 .BR EPERM .
-.PP
+.SS Closing the fanotify file descriptor
 To end listening, it is sufficient to
 .BR close (2)
 the fanotify file descriptor.