patch 8.2.4881: "P" in Visual mode still changes some registers

Problem:    "P" in Visual mode still changes some registers.
Solution:   Make "P" in Visual mode not change any register. (Shougo
            Matsushita, closes #10349)
diff --git a/runtime/doc/index.txt b/runtime/doc/index.txt
index 58a4861..190ce7c 100644
--- a/runtime/doc/index.txt
+++ b/runtime/doc/index.txt
@@ -939,7 +939,7 @@
 |v_K|		K		   run 'keywordprg' on the highlighted area
 |v_O|		O		   move horizontally to other corner of area
 |v_P|		P		   replace highlighted area with register
-				   contents; unnamed register is unchanged
+				   contents; registers are unchanged
 		Q		   does not start Ex mode
 |v_R|		R		2  delete the highlighted lines and start
 				   insert