Fix typo in memory documentation (langchain-ai#2165)

Author: EricHasegawa

docs/docs_skeleton/docs/modules/memory/index.mdx

@@ -19,7 +19,7 @@ Secondly, LangChain provides easy ways to incorporate these utilities into chain
 
 ## Get started
 
-Memory involves keeping a concept of state around throughout a user's interactions with an language model. A user's interactions with a language model are captured in the concept of ChatMessages, so this boils down to ingesting, capturing, transforming and extracting knowledge from a sequence of chat messages. There are many different ways to do this, each of which exists as its own memory type.
+Memory involves keeping a concept of state around throughout a user's interactions with a language model. A user's interactions with a language model are captured in the concept of ChatMessages, so this boils down to ingesting, capturing, transforming and extracting knowledge from a sequence of chat messages. There are many different ways to do this, each of which exists as its own memory type.
 
 In general, for each type of memory there are two ways to understanding using memory. These are the standalone functions which extract information from a sequence of messages, and then there is the way you can use this type of memory in a chain.