HMP: fix doc of dump-guest-memory

Signed-off-by: Qiao Nuohan <qiaonuohan@cn.fujitsu.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

hmp-commands.hx

@@ -1001,25 +1001,26 @@ ETEXI
     {
         .name       = "dump-guest-memory",
         .args_type  = "paging:-p,filename:F,begin:i?,length:i?",
-        .params     = "[-p] filename [begin] [length]",
-        .help       = "dump guest memory to file"
-                      "\n\t\t\t begin(optional): the starting physical address"
-                      "\n\t\t\t length(optional): the memory size, in bytes",
+        .params     = "[-p] filename [begin length]",
+        .help       = "dump guest memory into file 'filename'.\n\t\t\t"
+                      "-p: do paging to get guest's memory mapping.\n\t\t\t"
+                      "begin: the starting physical address.\n\t\t\t"
+                      "length: the memory size, in bytes.",
         .mhandler.cmd = hmp_dump_guest_memory,
     },
 
 
 STEXI
-@item dump-guest-memory [-p] @var{protocol} @var{begin} @var{length}
+@item dump-guest-memory [-p] @var{filename} @var{begin} @var{length}
 @findex dump-guest-memory
 Dump guest memory to @var{protocol}. The file can be processed with crash or
 gdb.
-  filename: dump file name
-    paging: do paging to get guest's memory mapping
+        -p: do paging to get guest's memory mapping.
+  filename: dump file name.
      begin: the starting physical address. It's optional, and should be
-            specified with length together.
+            specified together with length.
     length: the memory size, in bytes. It's optional, and should be specified
-            with begin together.
+            together with begin.
 ETEXI
 
     {