fix(README): Correct deepmerge example (#203)

`merge` takes 2 single objects, `merge.all` takes an array

Author: timja

Diff for: README.md

@@ -251,7 +251,7 @@ const { config } = await octokit.config.get({
   owner,
   repo,
   path: ".github/test.yml",
-  defaults: (configs) => deepmerge([defaults, ...configs]),
+  defaults: (configs) => deepmerge.all([defaults, ...configs]),
 });
 ```