HuggingFaceEndpoint: Correct Example for ImportError (#1176)

When I try to import the Class HuggingFaceEndpoint I get an Import
Error: cannot import name 'HuggingFaceEndpoint' from 'langchain'.
(langchain version 0.0.88)
These two imports work fine: from langchain import HuggingFacePipeline
and from langchain import HuggingFaceHub.

So I corrected the import statement in the example. There is probably a
better solution to this, but this fixes the Error for me.

langchain/__init__.py

@@ -28,6 +28,7 @@
     Cohere,
     ForefrontAI,
     GooseAI,
+    HuggingFaceEndpoint,
     HuggingFaceHub,
     OpenAI,
     Petals,
@@ -76,6 +77,7 @@
     "PromptTemplate",
     "ReActChain",
     "Wikipedia",
+    "HuggingFaceEndpoint",
     "HuggingFaceHub",
     "HuggingFacePipeline",
     "SQLDatabase",

langchain/llms/__init__.py

@@ -8,6 +8,7 @@
 from langchain.llms.cohere import Cohere
 from langchain.llms.forefrontai import ForefrontAI
 from langchain.llms.gooseai import GooseAI
+from langchain.llms.huggingface_endpoint import HuggingFaceEndpoint
 from langchain.llms.huggingface_hub import HuggingFaceHub
 from langchain.llms.huggingface_pipeline import HuggingFacePipeline
 from langchain.llms.nlpcloud import NLPCloud
@@ -26,6 +27,7 @@
     "NLPCloud",
     "OpenAI",
     "Petals",
+    "HuggingFaceEndpoint",
     "HuggingFaceHub",
     "HuggingFacePipeline",
     "AI21",
@@ -43,6 +45,7 @@
     "forefrontai": ForefrontAI,
     "gooseai": GooseAI,
     "huggingface_hub": HuggingFaceHub,
+    "huggingface_endpoint": HuggingFaceEndpoint,
     "nlpcloud": NLPCloud,
     "openai": OpenAI,
     "petals": Petals,

langchain/llms/huggingface_endpoint.py

@@ -23,7 +23,7 @@ class HuggingFaceEndpoint(LLM, BaseModel):
     Example:
         .. code-block:: python
 
-            from langchain import HuggingFaceEndpoint
+            from langchain.llms.huggingface_endpoint import HuggingFaceEndpoint
             endpoint_url = (
                 "https://abcdefghijklmnop.us-east-1.aws.endpoints.huggingface.cloud"
             )