chore: add placeholder version in README.md file (#1766)

ti-chi-bot · web-flow · commit 21181eef354e · 2024-12-31T05:45:09.000Z
diff --git a/README.md b/README.md
@@ -88,4 +88,4 @@ Copyright 2020 PingCAP, Inc.
 [pd]: https://github.com/pingcap/pd
 [asktug.com]: https://asktug.com/
 
-<!-- VERSION_PLACEHOLDER: v7.5.5 -->
+<!-- VERSION_PLACEHOLDER: v7.5.6 -->
