Update BENCHMARKING.md for GA release (#453)

Signed-off-by: Daniel Carl Jones <djonesoa@amazon.com>

doc/BENCHMARKING.md

@@ -1,5 +1,7 @@
 ## Benchmarking
-Currently, Mountpoint for Amazon S3 is an alpha release and we are focusing on delivering high throughput read support. In order to make sure that new changes do not introduce performance regression, we have created some performance benchmark as a part of our CI using [fio](https://github.com/axboe/fio), an awesome open-source application for file system benchmarking.
+
+Mountpoint for Amazon S3 is a simple, high-throughput file client for mounting an Amazon S3 bucket as a local file system.
+To avoid new changes introducing performance regressions, we run a performance benchmark on every commit using [fio](https://github.com/axboe/fio), an awesome open-source application for file system benchmarking.
 
 ### Workloads
 
@@ -46,4 +48,4 @@ You can use the following steps.
 
         ./mountpoint-s3/scripts/fs_bench.sh
 
-5. You should see the benchmark logs in `bench.out` file in the project root directory. The combined results will be saved into a JSON file at `results/output.json`.
+5. You should see the benchmark logs in `bench.out` file in the project root directory. The combined results will be saved into a JSON file at `results/output.json`.