readme: add the link to the tutorial (#489)

* Fix the wrong statement

* Fix a typo

* Fix the statement

* Fix the quotation mark

* Update the statement of tikv-ctl

* Update the MySQL related statement

* Update the statement regarding the MySQL client

* Add the link to the tutorial

README.md

@@ -6,6 +6,7 @@
   - [TiDB Introduction](overview.md#tidb-introduction)
   - [TiDB Architecture](overview.md#tidb-architecture)
 - [TiDB Quick Start Guide](QUICKSTART.md)
+- [TiDB Tutorial](https://www.pingcap.com/blog/how_to_spin_up_an_htap_database_in_5_minutes_with_tidb_tispark/)
 + TiDB User Guide
   + TiDB Server Administration
     - [The TiDB Server](sql/tidb-server.md)