Revise starts-with-template example

This test is believed to fail, so we should mark it with
`compile_fail` rather than `ignore`.

Let's wrap the comment.

The compiler's error message, in this case, doesn't add any insight;
let's remove the details of that.

Author: traviscross

src/inline-assembly.md

@@ -292,11 +292,12 @@ core::arch::global_asm!(
 r[asm.attributes.starts-with-template]
 Syntactically there must be at least one template string before the first operand.
 
-```rust, ignore
-// This is rejected because `a = out(reg) x` does not parse as a template string.
+```rust,compile_fail
+// This is rejected because `a = out(reg) x` does not parse as a
+// template string.
 core::arch::asm!(
     #[cfg(false)]
-    a = out(reg) x, //~ ERROR expected token: `,`
+    a = out(reg) x, // ERROR.
     "",
 );
 ```