docs(copilot): simplify Terminal Chat wording

Remove the repeated use of 'chat' after the Terminal Chat product name on both Windows Terminal guidance pages.

Changes:
- content/copilot/get-started/quickstart.md
  - Refer to the Terminal Chat window without repeating 'chat'.

- content/copilot/how-tos/chat-with-copilot/chat-in-windows-terminal.md
  - Use the same corrected Terminal Chat window wording.

Validation:
- npm run lint-content -- --paths content/copilot/get-started/quickstart.md content/copilot/how-tos/chat-with-copilot/chat-in-windows-terminal.md
- git diff --check

Author: raulkolaric

content/copilot/get-started/quickstart.md

@@ -126,7 +126,7 @@ After you've installed {% data variables.product.prodname_windows_terminal %} Ca
 
 1. Open **Terminal Chat (Experimental)** in the dropdown menu.
 
-1. In the Terminal Chat chat window, type `how do i list all markdown files in my directory` then press <kbd>Enter</kbd>.
+1. In the Terminal Chat window, type `how do i list all markdown files in my directory` then press <kbd>Enter</kbd>.
 
    {% data variables.product.prodname_copilot_short %}'s answer is displayed below your question.
 

content/copilot/how-tos/chat-with-copilot/chat-in-windows-terminal.md

@@ -25,7 +25,7 @@ If you have access to {% data variables.product.prodname_copilot %} via your org
 
 ## Getting command explanations and suggestions
 
-In the Terminal Chat chat window, type a question (for example, `how do i list all markdown files in my directory`) then press <kbd>Enter</kbd>.
+In the Terminal Chat window, type a question (for example, `how do i list all markdown files in my directory`) then press <kbd>Enter</kbd>.
 
    {% data variables.product.prodname_copilot_short %}'s answer is displayed below your question.