clone.2: Restructure text on CLONE_INTO_CGROUP use cases

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

man2/clone.2

@@ -559,6 +559,11 @@ Note that all of the usual restrictions (described in
 .BR cgroups (7))
 on placing a process into a version 2 cgroup apply.
 .IP
+Among the possible use cases for
+.BR CLONE_INTO_CGROUP
+are the following:
+.RS
+.IP * 3
 Spawning a process into a cgroup different from the parent's cgroup
 makes it possible for a service manager to directly spawn new
 services into dedicated cgroups.
@@ -566,6 +571,7 @@ This eliminates the accounting
 jitter that would be caused if the child process was first created in the
 same cgroup as the parent and then
 moved into the target cgroup.
+.IP *
 The
 .BR CLONE_INTO_CGROUP
 flag also allows the creation of
@@ -573,10 +579,12 @@ frozen child processes by spawning them into a frozen cgroup.
 (See
 .BR cgroups (7)
 for a description of the freezer controller.)
+.IP *
 For threaded applications (or even thread implementations which
 make use of cgroups to limit individual threads), it is possible to
 establish a fixed cgroup layout before spawning each thread
 directly into its target cgroup.
+.RE
 .TP
 .BR CLONE_IO " (since Linux 2.6.25)"
 If