docs/xbzrle: update 'cache miss rate' and 'encoding rate' to docs

Signed-off-by: Mao Zhongyi <maozhongyi@cmss.chinamobile.com>
Message-Id: <20200603080904.997083-9-maozhongyi@cmss.chinamobile.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
diff --git a/docs/xbzrle.txt b/docs/xbzrle.txt
index 385b499..6bd1828 100644
--- a/docs/xbzrle.txt
+++ b/docs/xbzrle.txt
@@ -113,9 +113,11 @@
     xbzrle transferred: I kbytes
     xbzrle pages: J pages
     xbzrle cache miss: K pages
-    xbzrle overflow: L
+    xbzrle cache miss rate: L
+    xbzrle encoding rate: M
+    xbzrle overflow: N
 
-xbzrle cache-miss: the number of cache misses to date - high cache-miss rate
+xbzrle cache miss: the number of cache misses to date - high cache-miss rate
 indicates that the cache size is set too low.
 xbzrle overflow: the number of overflows in the decoding which where the delta
 could not be compressed. This can happen if the changes in the pages are too