docs: update docs with cli usage

Author: soulteary

README.md

@@ -2,9 +2,25 @@
 
 Nginx configuration formatter under 10MB size.
 
+## Usage
+
+```bash
+Nginx Formatter
+
+Usage of ./nginx-formatter:
+  -char
+    	Indent char, defualt:   (default " ")
+  -indent int
+    	Indent size, defualt: 2 (default 2)
+  -input string
+    	Input directory
+  -output string
+    	Output directory
+```
+
 
 ## Docker
 
-<img src=".github/dockerhub.png" width="240" >
+<img src=".github/dockerhub.png" width="80%" >
 
 - https://hub.docker.com/r/soulteary/nginx-formatter