Update src/doc/rustdoc/src/what-is-rustdoc.md

Co-authored-by: Guillaume Gomez <[email protected]>

Author: harryhanYuhao

src/doc/rustdoc/src/what-is-rustdoc.md

@@ -80,7 +80,12 @@ docs. Instead of the `rustdoc` command, we could have done this:
 
 ```bash
 $ cargo doc
-$ cargo doc --open # automatically open
+```
+
+If you want `cargo` to open the generated documentation once generated, you can use:
+
+```bash
+$ cargo doc --open
 ```
 
 Internally, `cargo doc` calls out to `rustdoc` like this: