add py-mysql-elasticsearch-sync to readme, a project using pymyrepl

[jaehyeonpy]

• python-mysql-replication has its usage of 'MySQL to search engine replication', but there is only one usage that can be found in examples/logstash.
• The logstash thing is also a good usage, but I found it better to have more usage. So, I made py-mysql-elasticsearch-sync, which replicates mysql to elasticsearch using python-mysql-replication(https://github.com/jaehyeonpy/py-mysql-elasticsearch-sync).
• I would appreciate if you could merge this.

[julien-duponchelle]

Great !