tools: Add filesystem action examples to pyboard.py help.

Signed-off-by: Brianna Laugher <brianna.laugher@gmail.com>

docs/reference/pyboard.py.rst

@@ -48,7 +48,9 @@ Running ``pyboard.py --help`` gives the following output:
                             available
       --follow              follow the output after running the scripts
                             [default if no scripts given]
-      -f, --filesystem      perform a filesystem action
+      -f, --filesystem      perform a filesystem action: cp local :device | cp
+                            :device local | cat path | ls [path] | rm path | mkdir
+                            path | rmdir path
 
 Running a command on the device
 -------------------------------

tools/pyboard.py

@@ -651,7 +651,11 @@ def main():
         help="Do not follow the output after running the scripts.",
     )
     cmd_parser.add_argument(
-        "-f", "--filesystem", action="store_true", help="perform a filesystem action"
+        "-f",
+        "--filesystem",
+        action="store_true",
+        help="perform a filesystem action: "
+        "cp local :device | cp :device local | cat path | ls [path] | rm path | mkdir path | rmdir path",
     )
     cmd_parser.add_argument("files", nargs="*", help="input files")
     args = cmd_parser.parse_args()