Update readme and changelog

Author: ferdinand-beyer

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+- Add a `:response-executor` option to control on which thread responses to
+  server-initiated requests are run, defaulting to Promesa's `:default`
+  executor, i.e. `ForkJoinPool/commonPool`.
+
 ## v1.10.0
 
 - Add `textDocument/foldingRange` schemas.

README.md

@@ -120,6 +120,10 @@ Alternatively, you can convert the request to a promesa promise, and handle it u
 
 In this case `(promesa/cancel! request)` will send `$/cancelRequest`.
 
+Response promises are completed on Promesa's `:default` executor.  You
+can specify your own executor by passing the `:response-executor` option
+when creating your server instance.
+
 ### Start and stop a server
 
 The last step is to start the server you created earlier. Use `lsp4clj.server/start`. This method accepts two arguments, the server and a "context".