docs: fix usage for info command
It permits multiple keys, not just one:
```
$ USE_BAZEL_VERSION=5.3.0 bazel info bazel-bin output_base
bazel-bin: /shared/cache/bazel/user_base/251baecad3ceac0816c552f4544d71e1/execroot/build_aspect_cli/bazel-out/k8-fastbuild/bin
output_base: /shared/cache/bazel/user_base/251baecad3ceac0816c552f4544d71e1
```
Closes
-Usage: %{product} info <options> [key]
+Usage: %{product} info <options> [keys]
Displays information about the state of the %{product} process in the
form of several "key: value" pairs. This includes the locations of
@@ -7,8 +7,8 @@ several output directories. Because some of the
values are affected by the options passed to '%{product} build', the
info command accepts the same set of options.
-A single non-option argument may be specified (e.g. "%{product}-bin"), in
-which case only the value for that key will be printed.
+If arguments are specified, each should be one of the keys (e.g. "%{product}-bin").
+In this case only the value(s) for those keys will be printed.
If --show_make_env is specified, the output includes the set of key/value
pairs in the "Make" environment, accessible within BUILD files.
