update readme

readme.md

@@ -194,6 +194,15 @@ Following are the options that can be passed on the pdf2pic api:
 
 The parameter can also be a boolean, if `true` then the response type will be `base64` and if `false` then the response type will be `image`. 
 This is deprecated and will be removed in the next major version.
+
+## Version Compatibility  
+
+| pdf2pic version | node version     |
+|-----------------|------------------|
+| 1.4.0           | < 14.x           |
+| 2.1.4, 2.2.4    | >= 14.x          |
+| 3.1.1           | >= 14.x          |
+| >= 3.1.2        | >= 18.x          |
 
 ## Contributing
 * Fork it (https://github.com/yakovmeister/pdf2image/fork)