add README.MD

README.MD

+`sqlmd`is a tool for generating table create sql
+
+Here is an example
+
+````text
+# mx_user(table_name)
+```text(table_comment)
+用户表
+```
+(column info and * for primary key)
+name|type|remark|defaultvalue
+---|---|---|---
+*id|varchar(100)|主键|-
+name|varchar(100)|姓名|-
+email|varchar(100)|邮箱|-
+
+(index information)
+### idx_name
+- name
+- email
+````
+
+ctrl+c to copy markdown to clipboard and execute the command:
+
+```bash
+java -jar sqlmd.jar [oracle|mysql]
+```
+
+the result will output in the console and paste into clipboard. just ctrl+v.
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