[howto/source.rst] update unitd runtime options

add a `dir` suffix to the `modules`, `state` and `tmp` runtime options.

Author: kedartal

source/howto/source.rst

@@ -1132,18 +1132,18 @@ counterparts, see :ref:`here <source-config-src>`.
    * - **--log pathname**
      - Pathname for Unit's :ref:`log <troubleshooting-log>`.
 
-   * - **--modules directory**
+   * - **--modulesdir directory**
      - Directory path for Unit's language :doc:`modules <modules>`
        (***.unit.so** files).
 
    * - **--pid pathname**
      - Pathname for the PID file of Unit's :program:`main` :ref:`process
        <security-apps>`.
 
-   * - **--state directory**
+   * - **--statedir directory**
      - Directory path for Unit's state storage.
 
-   * - **--tmp directory**
+   * - **--tmpdir directory**
      - Directory path for Unit's temporary file storage.
 
 Finally, to stop a running Unit: