[doc] update doucmentation about new command source

docs/source/manual/openfpga_shell/openfpga_commands/basic_commands.rst

@@ -13,6 +13,27 @@ help
 
   Show help desk to list all the available commands
 
+source
+~~~~~~
+
+  Run a set of existing commands from a string stream or a file
+
+  .. option:: --command_stream <string>
+
+    A string/file stream which contains the commands to be executed. Use quote(``"``) to split between commands. For example,
+
+.. code-block::
+
+   source --command_stream "help;exit;"
+
+  .. option:: --from_file
+
+    Specify the command stream comes from a file. When selected, the file will be parsed as a regular script following the OpenFPGA script file format. See details in :ref:openfpga_script_format
+
+  .. option:: --batch_mode
+
+    Enable batch mode when executing the script from a file. Valid only when ``--from_file`` is enabled
+
 exit
 ~~~~