Improve clarity of mydumper warning. (pingcap#3719)

Null not nil · TomShawn · web-flow · commit 58eef526d046 · 2020-08-25T10:56:17.000+08:00
Co-authored-by: TomShawn &lt;41534398+TomShawn@users.noreply.github.com&gt;
diff --git a/mydumper-overview.md b/mydumper-overview.md
@@ -8,7 +8,7 @@ aliases: ['/docs/dev/mydumper-overview/','/docs/dev/reference/tools/mydumper/']
 
 > **Warning:**
 >
-> The maintainers have stopped developing new features for Mydumper, and most of its features have been replaced by [Dumpling](/dumpling-overview.md). It is strongly recommended that you switch to Dumpling.
+> PingCAP previously maintained a fork of the [mydumper project](https://github.com/maxbube/mydumper) with enhancements specific to TiDB. This fork has since been replaced by [Dumpling](/dumpling-overview.md), which has been rewritten in Go, and supports more optimizations that are specific to TiDB. It is strongly recommended that you use Dumpling instead of mydumper.
 
 ## What is Mydumper?
 

Original file line number	Diff line number	Diff line change
`@@ -8,7 +8,7 @@ aliases: ['/docs/dev/mydumper-overview/','/docs/dev/reference/tools/mydumper/']`
`8`	`8`
`9`	`9`	`> Warning:`
`10`	`10`	`>`
`11`		`-> The maintainers have stopped developing new features for Mydumper, and most of its features have been replaced by [Dumpling](/dumpling-overview.md). It is strongly recommended that you switch to Dumpling.`
	`11`	`+> PingCAP previously maintained a fork of the [mydumper project](https://github.com/maxbube/mydumper) with enhancements specific to TiDB. This fork has since been replaced by [Dumpling](/dumpling-overview.md), which has been rewritten in Go, and supports more optimizations that are specific to TiDB. It is strongly recommended that you use Dumpling instead of mydumper.`
`12`	`12`
`13`	`13`	`## What is Mydumper?`
`14`	`14`