Fix bugs in api and add examples (#3353)

### What problem does this PR solve?

Fix bugs in api.
Add simple examples for api.

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)
- [x] New Feature (non-breaking change which adds functionality)

---------

Co-authored-by: liuhua <10215101452@stu.ecun.edu.cn>
Co-authored-by: Kevin Hu <kevinhu.sh@gmail.com>

docs/references/http_api_reference.md

@@ -187,7 +187,9 @@ curl --request DELETE \
      --url http://{address}/api/v1/datasets \
      --header 'Content-Type: application/json' \
      --header 'Authorization: Bearer <YOUR_API_KEY>' \
-     --data '{"ids": ["test_1", "test_2"]}'
+     --data '{
+     "ids": ["test_1", "test_2"]
+     }'
 ```
 
 #### Request parameters
@@ -243,7 +245,7 @@ curl --request PUT \
      --header 'Authorization: Bearer <YOUR_API_KEY>' \
      --data '
      {
-          "name": "updated_dataset",
+          "name": "updated_dataset"
      }'
 ```
 
@@ -1152,7 +1154,7 @@ curl --request PUT \
      --data '
      {   
           "content": "ragflow123",  
-          "important_keywords": [],   
+          "important_keywords": []  
      }'
 ```