[Refactor] Converge Pipeline and App classes (#1021)

Co-authored-by: Deven Patel <deven298@yahoo.com>

docs/api-reference/pipeline/query.mdx

@@ -36,7 +36,7 @@ title: '❓ query'
 If you want to get the answer to question and return both answer and citations, use the following code snippet:
 
 ```python With Citations
-from embedchain import Pipeline as App
+from embedchain import App
 
 # Initialize app
 app = App()
@@ -78,7 +78,7 @@ When `citations=True`, note that the returned `sources` are a list of tuples whe
 If you just want to return answers and don't want to return citations, you can use the following example:
 
 ```python Without Citations
-from embedchain import Pipeline as App
+from embedchain import App
 
 # Initialize app
 app = App()