Fix #1439: describe svelte-jsoneditor in the readme

Author: josdejong

README.md

@@ -21,6 +21,11 @@ Cross browser testing for JSONEditor is generously provided by <a href="https://
 
 <a href="https://www.browserstack.com" target="_blank"><img alt="BrowserStack" src="https://raw.github.com/josdejong/jsoneditor/master/misc/browserstack.png"></a>
 
+## Successor: svelte-jsoneditor
+
+This library [`jsoneditor`](https://github.com/josdejong/jsoneditor) has a successor: [`svelte-jsoneditor`](https://github.com/josdejong/svelte-jsoneditor). The new editor is not a one-to-one replacement, so there may be reasons to stick with `jsoneditor`. 
+The main differences between the two [are described here](https://github.com/josdejong/svelte-jsoneditor#differences-between-josdejongsvelte-jsoneditor-and-josdejongjsoneditor).
+
 ## Features
 
 JSONEditor has various modes, with the following features.