tools/memleak: Fixes explanations for -Z and -z options

These are the description of each options written in memleak.c file
-z option: capture only allocations larger than this size
-Z option: capture only allocations smaller than this size

But actually they work like this
-z option: capture only allocations larger than or equal to this size
-Z option: capture only allocations smaller than or equal to this size

Which means, there was off-by-one errors.
So, fixes the explanation message.

tools/memleak.py

@@ -104,9 +104,9 @@ def run_command_get_pid(command):
 parser.add_argument("-T", "--top", type=int, default=10,
         help="display only this many top allocating stacks (by size)")
 parser.add_argument("-z", "--min-size", type=int,
-        help="capture only allocations larger than this size")
+        help="capture only allocations larger than or equal to this size")
 parser.add_argument("-Z", "--max-size", type=int,
-        help="capture only allocations smaller than this size")
+        help="capture only allocations smaller than or equal to this size")
 parser.add_argument("-O", "--obj", type=str, default="c",
         help="attach to allocator functions in the specified object")
 parser.add_argument("--ebpf", action="store_true",

tools/memleak_example.txt

@@ -217,9 +217,9 @@ optional arguments:
                         sample every N-th allocation to decrease the overhead
   -T TOP, --top TOP     display only this many top allocating stacks (by size)
   -z MIN_SIZE, --min-size MIN_SIZE
-                        capture only allocations larger than this size
+                        capture only allocations larger than or equal to this size
   -Z MAX_SIZE, --max-size MAX_SIZE
-                        capture only allocations smaller than this size
+                        capture only allocations smaller than or equal to this size
   -O OBJ, --obj OBJ     attach to allocator functions in the specified object
   --sort KEY            report sorted in given key; available key list: size,
                         count