Auto merge of #4675 - mgeisler:align-cmdline-examples, r=alexcrichton

Align command line examples in "cargo help test"

The initial example used an indentation of four spaces, the other
examples used only two spaces. They now all use four spaces.

I checked all other Cargo commands and found no other such problems.

src/bin/test.rs

@@ -101,19 +101,19 @@ for the --jobs argument is the number of CPUs. If you want to control the
 number of simultaneous running test cases, pass the `--test-threads` option
 to the test binaries:
 
-  cargo test -- --test-threads=1
+    cargo test -- --test-threads=1
 
 Compilation can be configured via the `test` profile in the manifest.
 
 By default the rust test harness hides output from test execution to
 keep results readable. Test output can be recovered (e.g. for debugging)
 by passing `--nocapture` to the test binaries:
 
-  cargo test -- --nocapture
+    cargo test -- --nocapture
 
 To get the list of all options available for the test binaries use this:
 
-  cargo test -- --help
+    cargo test -- --help
 ";
 
 pub fn execute(options: Options, config: &mut Config) -> CliResult {