Merge branch 'jk/run-command-use-shell-doc'

The .use_shell flag in struct child_process that is passed to
run_command() API has been clarified with a bit more documentation.

* jk/run-command-use-shell-doc:
  run-command: document use_shell option

Author: gitster

run-command.h

@@ -126,8 +126,15 @@ struct child_process {
 	 */
 	unsigned silent_exec_failure:1;
 
-	unsigned stdout_to_stderr:1;
+	/**
+	 * Run the command from argv[0] using a shell (but note that we may
+	 * still optimize out the shell call if the command contains no
+	 * metacharacters). Note that further arguments to the command in
+	 * argv[1], etc, do not need to be shell-quoted.
+	 */
 	unsigned use_shell:1;
+
+	unsigned stdout_to_stderr:1;
 	unsigned clean_on_exit:1;
 	unsigned wait_after_clean:1;
 	void (*clean_on_exit_handler)(struct child_process *process);