add usage

Author: jiro4989

README.rst

@@ -4,24 +4,36 @@ codepoint
 
 |nimble-version| |nimble-install| |gh-actions|
 
-TODO
-
-This is a Nim project template.
-You must run command at first.
-
-.. code-block:: shell
-
-   nim c tool/setup.nim
-   tool/setup --author:<yourname> --appname:<application_name>
-
-This command replace and rename template strings of this repository.
+codepoint prints codepoint of characters.
 
 .. contents:: Table of contents
 
 Usage
 =====
 
-TODO
+Basic usage.
+
+.. code-block:: shell
+
+   $ echo 'hello world' | codepoint
+   char code_point code_point(hex)
+   h 104 \U68
+   e 101 \U65
+   l 108 \U6C
+   l 108 \U6C
+   o 111 \U6F
+     32 \U20
+   w 119 \U77
+   o 111 \U6F
+   r 114 \U72
+   l 108 \U6C
+   d 100 \U64
+
+   # Multibyte characters
+   $ echo '寿司' | codepoint
+   char code_point code_point(hex)
+   寿 23551 \U5BFF
+   司 21496 \U53F8
 
 Installation
 ============