Update README.md

Author: vutrandn94

README.md

@@ -2,3 +2,16 @@
 Backup & Restore PostgreSQL
 
 *Backup will be stored in folder with format "%d%m%Y"*
+
+## Detailed information of variables
+
+| Variable | Describe |
+| :--- | :--- |
+| PGUSER | PostgreSQL login user (Default: root) |
+| PGPASSWORD | PostgreSQL password login user |
+| PGPORT | PostgreSQL port connection (Default: 5432) |
+| PGHOST | PostgreSQL host connection (Default: localhost) |
+| DB_EXCLUDE | Exclude database backups |
+| BACKUP_FOLDER | Folder storage backups |
+| ROTATE_KEEP | Specify the number of backup copies to keep (Default: 7)|
+| BACKUP_DIR | Exact path to the folder storing the backup files in (.sql) format that need to be restored |