doc: Clarify behavior of --watch-path and --watch flags

Author: juanibe

doc/api/cli.md

@@ -3056,6 +3056,10 @@ Use `--watch-path` to specify what paths to watch.
 This flag cannot be combined with
 `--check`, `--eval`, `--interactive`, or the REPL.
 
+Note: The `--watch` flag requires a file path as an argument. It does not support
+being used with `--run` or inline script input. If no file is provided, Node.js will
+exit with status code 9.
+
 ```bash
 node --watch index.js
 ```
@@ -3083,6 +3087,9 @@ combination with `--watch`.
 This flag cannot be combined with
 `--check`, `--eval`, `--interactive`, `--test`, or the REPL.
 
+Note: Using `--watch-path` implicitly enables `--watch`, which requires a file path
+and is incompatible with `--run`, as `--run` takes precedence and ignores watch mode.
+
 ```bash
 node --watch-path=./src --watch-path=./tests index.js
 ```