btrfs-progs: update wording for qgroup limits

Based on a user report, 'max' in help does not clearly point to the
limits that are commonly used as a quota-related term.

Signed-off-by: David Sterba <dsterba@suse.cz>

Documentation/btrfs-qgroup.txt

@@ -82,9 +82,9 @@ print parent qgroup id.
 -c::::
 print child qgroup id.
 -r::::
-print max referenced size of qgroup.
+print limit of referenced size of qgroup.
 -e::::
-print max exclusive size of qgroup.
+print limit of exclusive size of qgroup.
 -F::::
 list all qgroups which impact the given path(include ancestral qgroups)
 -f::::

cmds-qgroup.c

@@ -210,12 +210,12 @@ static const char * const cmd_qgroup_show_usage[] = {
 	"Show subvolume quota groups.",
 	"-p             print parent qgroup id",
 	"-c             print child qgroup id",
-	"-r             print max referenced size of qgroup",
-	"-e             print max exclusive size of qgroup",
-	"-F             list all qgroups which impact the given path"
-	"(include ancestral qgroups)",
-	"-f             list all qgroups which impact the given path"
-	"(exclude ancestral qgroups)",
+	"-r             print limit of referenced size of qgroup",
+	"-e             print limit of exclusive size of qgroup",
+	"-F             list all qgroups which impact the given path",
+	"               (including ancestral qgroups)",
+	"-f             list all qgroups which impact the given path",
+	"               (excluding ancestral qgroups)",
 	"--raw          raw numbers in bytes",
 	"--human-readable",
 	"               human firendly numbers in given base, 1024 by default",