Update output of venv -h

* Update description of the --system-site-packages option
* Show --copies option in the usage

Doc/using/venv-create.inc

@@ -29,8 +29,9 @@ or equivalently::
 
 The command, if run with ``-h``, will show the available options::
 
-    usage: venv [-h] [--system-site-packages] [--symlinks] [--clear]
-                [--upgrade] [--without-pip] ENV_DIR [ENV_DIR ...]
+    usage: venv [-h] [--system-site-packages] [--symlinks | --copies] [--clear]
+                [--upgrade] [--without-pip]
+                ENV_DIR [ENV_DIR ...]
 
     Creates virtual Python environments in one or more target directories.
 
@@ -39,8 +40,8 @@ The command, if run with ``-h``, will show the available options::
 
     optional arguments:
       -h, --help             show this help message and exit
-      --system-site-packages Give access to the global site-packages dir to the
-                             virtual environment.
+      --system-site-packages Give the virtual environment access to the system
+                             site-packages dir.
       --symlinks             Try to use symlinks rather than copies, when symlinks
                              are not the default for the platform.
       --copies               Try to use copies rather than symlinks, even when