docs(benchtool): add benchtool to repo README and add workload paragraph (#171)

Author: jtlisi

README.md

@@ -2,6 +2,8 @@
 
 This repo contains tools used for interacting with [Cortex](https://github.com/cortexproject/cortex).
 
+* [benchtool](docs/benchtool.md): A powerful YAML driven tool for benchmarking
+  Cortex write and query API.
 * [cortextool](#cortextool): Interacts with user-facing Cortex APIs and backend storage components
 * [chunktool](#chunktool): Interacts with chunks stored and indexed in Cortex storage backends.
 * [logtool](#logtool): Tool which parses Cortex query-frontend logs and formats them for easy analysis.

docs/benchtool.md

@@ -10,7 +10,10 @@ expanded functionality and this should not be consided stable.
 
 ## Workload file
 
-The workload file can be configured as a follows:
+The `benchtool` is designed to generate Prometheus remote-write and PromQL API
+query requests to a configured endpoint. The characteristics of the data used
+for these requests is driven by a YAML workload configuration file. The workload
+file can be configured as a follows:
 
 ```yaml
 replicas: "<int>"
@@ -165,3 +168,4 @@ value of the benchtool instance.
 
 This will ensure two `benchtool` processes run with the same id and workload
 config file will result in the same behavior between runs.
+