Update README

README.md

@@ -5,10 +5,12 @@
 **This is still being developed and isn't ready for production!**
 Only tested with gerbers generated by EAGLE.
 
-Requires node version 10 or higher.
+node version 20 or higher recommended.
 
 ## Usage
+
 ### Save a PNG file
+
 ```
 const { ImageGenerator } = require('@nplayfair/npe_gerber');
 
@@ -41,7 +43,9 @@ fileProc.gerberToImage(gerberArchive)
         console.log(`Generated image ${filename}`);
       })
 ```
+
 ### Return a PNG stream
+
 ```
 const { ImageGenerator } = require('@nplayfair/npe_gerber');
 
@@ -74,6 +78,7 @@ fileProc.gerberToStream(gerberArchive)
         // Do something with the stream
       })
 ```
+
 ## Layer Names
 
 The constructor must be passed an array of filenames that correspond to the layers in the gerber archives you expect to be uploaded. The example above shows which names are used by EAGLE but other applications may use different filenames.