Fix typos in Copilot chat documentation

Author: HemantGaur

powerapps-docs/maker/TOC.yml

@@ -1691,7 +1691,7 @@
           href: ./model-driven-apps/copilot-chat-mda-knowledge.md
         - name: Add topics to Copilot chat
           href: ./model-driven-apps/copilot-chat-send-messages.mda
-        - name: Send rich messages to Copilot chat
+        - name: Send a messages to Copilot chat
           href: ./model-driven-apps/copilot-chat-send-messages.md
         - name: Prompt guide customizations
           href: ./model-driven-apps/copilot-chat-prompt-guide.md

powerapps-docs/maker/model-driven-apps/copilot-chat-send-messages.mda

@@ -17,7 +17,7 @@ contributors:
 ms.collection: bap-ai-copilot
 ai-usage: ai-assisted
 ---
-# Send message to Copilot chat in model-driven apps (preview)
+# Send a message to Copilot chat (preview)
 
 [!INCLUDE [cc-beta-prerelease-disclaimer](../../includes/cc-beta-prerelease-disclaimer.md)]
 
@@ -64,4 +64,4 @@ For more details see [send a message Copiot studio documentation](/microsoft-cop
 
 
 
-
+