Merge pull request #7119 from sinsharat/add_load_test_tool

tools: Add etcd 3.0 load test tool refernece

Documentation/libraries-and-tools.md

@@ -14,6 +14,7 @@
 - [etcdtool](https://github.com/mickep76/etcdtool) - Export/Import/Edit etcd directory as JSON/YAML/TOML and Validate directory using JSON schema
 - [etcd-rest](https://github.com/mickep76/etcd-rest) - Create generic REST API in Go using etcd as a backend with validation using JSON schema
 - [etcdsh](https://github.com/kamilhark/etcdsh) - A command line client with support of command history and tab completion. Supports v2
+- [etcdloadtest](https://github.com/sinsharat/etcdloadtest) - A command line load test client for etcd version 3.0 and above.
 
 **Go libraries**