README: resize logo, use markdown img syntax (pingcap#2609)

README.md

@@ -1,4 +1,4 @@
-<img src="docs/logo_with_text.png" height=100></img>
+![](docs/logo_with_text.png)
 
 [![Build Status](https://travis-ci.org/pingcap/tidb.svg?branch=master)](https://travis-ci.org/pingcap/tidb)
 [![Go Report Card](https://goreportcard.com/badge/github.com/pingcap/tidb)](https://goreportcard.com/report/github.com/pingcap/tidb)
@@ -10,25 +10,25 @@
 TiDB (The pronunciation is: /'taɪdiːbi:/ tai-D-B, etymology: titanium) is a distributed SQL database.
 Inspired by the design of Google [F1](http://research.google.com/pubs/pub41344.html), TiDB supports the best features of both traditional RDBMS and NoSQL.
 
-- __Horizontal scalability__  
+- __Horizontal scalability__
 Grow TiDB as your business grows. You can increase the capacity simply by adding more machines.
 
-- __Asynchronous schema changes__  
+- __Asynchronous schema changes__
 Evolve TiDB schemas as your requirement evolves. You can add new columns and indices without stopping or affecting the on-going operations.
 
-- __Consistent distributed transactions__  
+- __Consistent distributed transactions__
 Think of TiDB as a single-machine RDBMS. You can start a transaction that crosses multiple machines without worrying about consistency. TiDB makes your application code simple and robust.
 
-- __Compatible with MySQL protocol__  
+- __Compatible with MySQL protocol__
 Use TiDB as MySQL. You can replace MySQL with TiDB to power your application without changing a single line of code in most cases.
 
-- __Written in Go__  
+- __Written in Go__
 Enjoy TiDB as much as we love Go. We believe Go code is both easy and enjoyable to work with. Go makes us improve TiDB fast and makes it easy to dive into the codebase.
 
-- __NewSQL over TiKV__  
+- __NewSQL over TiKV__
   Turn [TiKV](https://github.com/pingcap/tikv) into NewSQL database.
 
-- __Multiple storage engine support__  
+- __Multiple storage engine support__
 Power TiDB with your most favorite engines. TiDB supports many popular storage engines in single-machine mode. You can choose from GolevelDB, LevelDB, RocksDB, LMDB, BoltDB and even more to come.
 
 For more details, read our blog [How we build TiDB](https://pingcap.github.io/blog/2016/10/17/how-we-build-tidb/)