Update documentation on aquery output format.
RELNOTES: None
@@ -2138,9 +2138,9 @@ Examples:
<p>
The tool accepts several command-line options.
- <code class='flag'>--output</code> selects the output format
- (<code>proto</code> is the default, use <code>text</code> for human readable
- output).
+ <code class='flag'>--output</code> selects the output format. The default output format
+ (<code>text</code>) is human-readable, use <code>proto</code> or <code>textproto</code> for
+ machine-readable format.
Notably, the aquery command runs on top of a regular Bazel build and inherits
the set of options available during a build.
</p>
