Update install-ubuntu.md
Fixed small grammatical error (sending this doc change through GH to demonstrate how this change process looks for a completely external contributor, see also https://github.com/bazelbuild/bazel/pull/2784)
Closes
@@ -40,7 +40,7 @@ want to install the testing version of Bazel, replace `stable` with `testing`.
sudo apt-get update && sudo apt-get install bazel
```
-Once installed, you can upgrade to newer version of Bazel with:
+Once installed, you can upgrade to a newer version of Bazel with:
```bash
sudo apt-get upgrade bazel
