fix copyright and update readme

README.md

@@ -1,10 +1,18 @@
 ## Yet another lisp interpreter
 
+**PRO**cessor of **L**ist for Mathematical Calculation
+
 It's a simple minimal lisp interpreter written by ruby.
 
+![](./screenshot/demo.png)
 
+### Feature
 
-### usage
+- Basic functions as a minimal lisp
+- **No** support for `String`
 
-- uncomment repl() in `minlisp.rb`
-- run it
+### Usage
+
+```bash
+$ ruby ./prol.rb
+```

prol.rb

@@ -102,7 +102,7 @@ def lisp_eval(elem, env = $global_env)
 end
 
 $copyleft = "Copyleft (Ↄ) 2021 vonhyou@lenva.tech
-(PRO)cessor of (L)ist for Mathmatical Calculation
+(PRO)cessor of (L)ist for Mathematical Calculation
 This is an open source software, you can view it's source code on github:
 https://github.com/vonhyou/lisp-interpreter\n\n"