updating readme to reflect the new changes in external-sources

Signed-off-by: Pouyan Khodabakhsh <[email protected]>

README.md

@@ -279,9 +279,11 @@ feature is currently disabled by default. To enable this feature add the followi
 ```yaml
 external-sources:
   enable: true
+  abort-after: 10m
   maven:
-    search-upstream-by-sha1: true
+    search-upstream: true
     base-url: https://search.maven.org/solrsearch/select
+    abort-after: 5m #override the global config
 ```
 
 You can also configure the base-url if you're using another registry as your maven endpoint.