xbzrle: update xbzrle doc

Add new parameter description, also:
1. Remove unsociable space.
2. Nit picking: s/two/2 in report

Signed-off-by: Mao Zhongyi <maozhongyi@cmss.chinamobile.com>
Message-Id: <20200320143216.423374-1-maozhongyi@cmss.chinamobile.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

docs/xbzrle.txt

@@ -92,6 +92,11 @@ Usage
 power of 2. The cache default value is 64MBytes. (on source only)
     {qemu} migrate_set_cache_size 256m
 
+Commit 73af8dd8d7 "migration: Make xbzrle_cache_size a migration parameter"
+(v2.11.0) deprecated migrate-set-cache-size, therefore, the new parameter
+is recommended.
+    {qemu} migrate_set_parameter xbzrle-cache-size 256m
+
 4. Start outgoing migration
     {qemu} migrate -d tcp:destination.host:4444
     {qemu} info migrate
@@ -108,7 +113,7 @@ power of 2. The cache default value is 64MBytes. (on source only)
     xbzrle transferred: I kbytes
     xbzrle pages: J pages
     xbzrle cache miss: K
-    xbzrle overflow : L
+    xbzrle overflow: L
 
 xbzrle cache-miss: the number of cache misses to date - high cache-miss rate
 indicates that the cache size is set too low.

migration/migration.c

@@ -1243,7 +1243,7 @@ static bool migrate_params_check(MigrationParameters *params, Error **errp)
         error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                    "xbzrle_cache_size",
                    "is invalid, it should be bigger than target page size"
-                   " and a power of two");
+                   " and a power of 2");
         return false;
     }
 

monitor/hmp-cmds.c

@@ -303,7 +303,7 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict)
                        info->xbzrle_cache->cache_miss);
         monitor_printf(mon, "xbzrle cache miss rate: %0.2f\n",
                        info->xbzrle_cache->cache_miss_rate);
-        monitor_printf(mon, "xbzrle overflow : %" PRIu64 "\n",
+        monitor_printf(mon, "xbzrle overflow: %" PRIu64 "\n",
                        info->xbzrle_cache->overflow);
     }