Fix wrong syntax on debug section

`explain()` or `profile()` can not be used after `first()` as described on docs.

Author: iget-master

README.md

@@ -424,15 +424,13 @@ There are two methods that can help you to analyze results of a search query:
 
     ```php
     App\MyModel::search('Brazil')
-        ->first()
         ->explain();
     ```
 
 * [profile](https://www.elastic.co/guide/en/elasticsearch/reference/current/search-profile.html)
 
     ```php
     App\MyModel::search('Brazil')
-        ->first()
         ->profile();
     ```
 
@@ -445,4 +443,4 @@ App\MyModel::search('Brazil')
     ->buildPayload();
 ```
 
-Note, that this method returns a collection of payloads, because of possibility of using multiple search rules in one query. 
+Note, that this method returns a collection of payloads, because of possibility of using multiple search rules in one query.