cgroup_namespaces.7: Some minor wording fixes and clarifications

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

man7/cgroup_namespaces.7

@@ -37,9 +37,11 @@ as seen via
 and
 .IR /proc/[pid]/mountinfo .
 
-Each cgroup namespace has its own set of cgroup root directories,
-which are the base points for the relative locations displayed in
-.IR /proc/[pid]/cgroup .
+Each cgroup namespace has its own set of cgroup root directories.
+These root directories are the base points for the relative
+locations displayed in the corresponding records in the
+.IR /proc/[pid]/cgroup
+file.
 When a process creates a new cgroup namespace using
 .BR clone (2)
 or
@@ -55,7 +57,8 @@ and the cgroups version 2 unified hierarchy.)
 When viewing
 .IR /proc/[pid]/cgroup ,
 the pathname shown in the third field of each record will be
-relative to the reading process's cgroup root directory.
+relative to the reading process's root directory
+for the corresponding cgroup hierarchy.
 If the cgroup directory of the target process lies outside
 the root directory of the reading process's cgroup namespace,
 then the pathname will show
@@ -95,7 +98,8 @@ files of, respectively, the new shell process started by the
 .BR unshare (1)
 command, a process that is in the original cgroup namespace
 .RI ( init ,
-with PID 1), and a process in a sibling cgroup:
+with PID 1), and a process in a sibling cgroup
+.RI ( sub2 ):
 
 .nf
 .in +4n
@@ -119,7 +123,9 @@ we see the following anomaly:
 .in
 .fi
 
-The fourth field of this file should show the
+The fourth field of this line
+.RI ( /.. )
+should show the
 directory in the cgroup filesystem which forms the root of this mount.
 Since by the definition of cgroup namespaces, the process's current
 freezer cgroup directory became its root freezer cgroup directory,