docs: update langchain integration docs as the Document has moved to …

…langchain_core (apify#934)

- update langchain integration as the Document has moved to
langchain_core and ApifyWrapper to langchain_community.
- change langchain URL links

sources/platform/integrations/langchain.md

@@ -20,18 +20,18 @@ but if you prefer to use JavaScript, you can follow the same steps in the [JavaS
 
 Before we start with the integration, we need to install all dependencies:
 
-`pip install apify-client langchain openai`
+`pip install apify-client langchain langchain_community openai tiktoken`
 
 After successful installation of all dependencies, we can start writing code.
 
-First, import `os`, `Document`, `VectorstoreIndexCreator`, and `ApifyWrapper` into your source code:
+First, import `os`, `VectorstoreIndexCreator`, `ApifyWrapper`, and `Document` into your source code:
 
 ```python
 import os
 
-from langchain.document_loaders.base import Document
 from langchain.indexes import VectorstoreIndexCreator
-from langchain.utilities import ApifyWrapper
+from langchain_community.utilities import ApifyWrapper
+from langchain_core.document_loaders.base import Document
 ```
 
 Find your [Apify API token](https://console.apify.com/account/integrations) and [OpenAI API key](https://platform.openai.com/account/api-keys) and initialize these into environment variable:
@@ -50,7 +50,7 @@ apify = ApifyWrapper()
 
 loader = apify.call_actor(
     actor_id="apify/website-content-crawler",
-    run_input={"startUrls": [{"url": "https://python.langchain.com/en/latest/"}], "maxCrawlPages": 10, "crawlerType": "cheerio"},
+    run_input={"startUrls": [{"url": "https://python.langchain.com/docs/get_started/introduction"}], "maxCrawlPages": 10, "crawlerType": "cheerio"},
     dataset_mapping_function=lambda item: Document(
         page_content=item["text"] or "", metadata={"source": item["url"]}
     ),
@@ -80,9 +80,9 @@ If you want to test the whole example, you can simply create a new file, `langch
 ```python
 import os
 
-from langchain.document_loaders.base import Document
 from langchain.indexes import VectorstoreIndexCreator
-from langchain.utilities import ApifyWrapper
+from langchain_community.utilities import ApifyWrapper
+from langchain_core.document_loaders.base import Document
 
 os.environ["OPENAI_API_KEY"] = "Your OpenAI API key"
 os.environ["APIFY_API_TOKEN"] = "Your Apify API token"
@@ -91,7 +91,7 @@ apify = ApifyWrapper()
 
 loader = apify.call_actor(
     actor_id="apify/website-content-crawler",
-    run_input={"startUrls": [{"url": "https://python.langchain.com/en/latest/"}], "maxCrawlPages": 10, "crawlerType": "cheerio"},
+    run_input={"startUrls": [{"url": "https://python.langchain.com/docs/get_started/introduction"}], "maxCrawlPages": 10, "crawlerType": "cheerio"},
     dataset_mapping_function=lambda item: Document(
         page_content=item["text"] or "", metadata={"source": item["url"]}
     ),
@@ -118,7 +118,7 @@ LangChain is a standard interface through which you can interact with a variety
 
 ## Resources
 
-- <https://python.langchain.com/docs/get_started/introduction/>
+- <https://python.langchain.com/docs/get_started/introduction>
 - <https://python.langchain.com/docs/integrations/providers/apify>
 - <https://python.langchain.com/docs/integrations/tools/apify>
 - <https://python.langchain.com/docs/modules/model_io/llms/>