Update README.md (#253)

hi folks!
i am only a novice and kindly don't take offence to my humble suggestion listed below.

logger channel = pimcore.elasicsearch may be replaced with
logger channel = pimcore.elasticsearch

this spell-check is essential since it is involved in the auto-generated DependecnyInjection script files.

README.md

@@ -26,7 +26,7 @@ pimcore_elasticsearch_client:
             hosts: ['elastic:9200']
             username: 'elastic'
             password: 'somethingsecret'
-            logger_channel: 'pimcore.elasicsearch'        
+            logger_channel: 'pimcore.elasticsearch'        
 
 
 # Define the client to be used by advanced object search