Fix bad spellings for 'convenience' (#3936)

Found in the docs for chat prompt templates:

https://python.langchain.com/en/latest/getting_started/getting_started.html#chat-prompt-templates

and fixed similar issues in neighboring notebooks.

docs/modules/models/chat/getting_started.ipynb

@@ -200,7 +200,7 @@
    "source": [
     "You can make use of templating by using a `MessagePromptTemplate`. You can build a `ChatPromptTemplate` from one or more `MessagePromptTemplates`. You can use `ChatPromptTemplate`'s `format_prompt` -- this returns a `PromptValue`, which you can convert to a string or Message object, depending on whether you want to use the formatted value as input to an llm or chat model.\n",
     "\n",
-    "For convience, there is a `from_template` method exposed on the template. If you were to use this template, this is what it would look like:"
+    "For convenience, there is a `from_template` method exposed on the template. If you were to use this template, this is what it would look like:"
    ]
   },
   {

docs/modules/models/chat/integrations/openai.ipynb

@@ -79,7 +79,7 @@
    "source": [
     "You can make use of templating by using a `MessagePromptTemplate`. You can build a `ChatPromptTemplate` from one or more `MessagePromptTemplates`. You can use `ChatPromptTemplate`'s `format_prompt` -- this returns a `PromptValue`, which you can convert to a string or Message object, depending on whether you want to use the formatted value as input to an llm or chat model.\n",
     "\n",
-    "For convience, there is a `from_template` method exposed on the template. If you were to use this template, this is what it would look like:"
+    "For convenience, there is a `from_template` method exposed on the template. If you were to use this template, this is what it would look like:"
    ]
   },
   {