Update README.md to show --help options

README.md

@@ -58,19 +58,19 @@ This is a pretty standard Python project so install however you'd do that from s
 $ pip install -e .
 ```
 
-## Get a LAP file
+## Get a LAP file via disassembly
 
 You need to run code in the `elisp/dedis.el` to produce disassembly
 that you'd write to a file that ends in `.lap`.  We have a number of
 sample LAP files in `testdata` in case you want to try a canned example.
 
 The specific functions in `dedis.el` are `disassemble-file` and `disassemble-full`.
 
-So inside Emacs find a function you want to disassemble and run `M-x disassemble-full`. Or find a bytecode file you want and run or `M-x disassembe-file`
+So inside Emacs find a function you want to disassemble and run `M-x disassemble-full`. Or find a bytecode file you want and run or `M-x disassemble-file`
 
 The first is like `disassemble`, but we don't truncate the output of docstrings or other things that `disassemble` generally does. The second is like `disassemble-full` but we start out with a bytecode file instead of a lisp function.
 
-## Disassemble LAP file
+## Decompile LAP file
 
 After you have written the results of the last section to LAP file, the file should end in `.lap`, and have set up the Python code, you can try to disassemble:
 
@@ -82,6 +82,29 @@ There is perhaps a *lot* of debug output. There is even some flow control that i
 
 Also, what we can decompile right now is a bit limited. I see no technical difficulties other than lots of work. So please help out.
 
+### decompiler options
+
+Here is the help usage for `lapdecompile`:
+
+```
+$ python ./lapdecompile/main.py --help
+Usage: main.py [OPTIONS] LAP_FILENAME
+
+  Lisp Assembler Program (LAP) decompiler
+
+Options:
+  -a, --assembly / --no-assembly  Show LAP assembly
+  -G, --graphs / --no-graphs      Produce dot/png control-flow graphs
+  -g, --grammar / --no-grammar    Show grammar reductions
+  --tree [after|before|full|none]
+                                  Show parse tree
+  -t                              alias for --tree=after
+  -T                              alias for --tree=full
+  --help                          Show this message and exit.
+```
+
+One of the cool options options `-G` or `--graphs` will produce dot/png control flow and dominator tree graphs.
+
 # But is it worth it?
 
 A number of people have opined that you really don't need a decompiler.