Add section on updating Copilot CLI

[kaviraj07]

Why:

Closes: #44459

What's being changed (if available, include any code snippets, screenshots, or gifs):

Added a pointer under the Next steps section of content/copilot/how-tos/copilot-cli/set-up-copilot-cli/install-copilot-cli.md directing users to the CLI command reference for the list of commands, including the command to update.

Per reviewer and CLI-team feedback, this keeps the install article focused on first-time installation and links to the canonical reference rather than duplicating command details.

Check off the following:

• A subject matter expert (SME) has reviewed the technical accuracy of the content in this PR. In most cases, the author can be the SME. Open source contributions may require an SME review from GitHub staff.
• The changes in this PR meet the docs fundamentals that are required for all content.
• All CI checks are passing and the changes look good in the review environment.

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Source	Review	Production	What Changed
copilot/how-tos/copilot-cli/set-up-copilot-cli/install-copilot-cli.md	fpt ghec	fpt ghec

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[Sharra-writes]

@kaviraj07 Normally I would say that this should be added to "next steps" at the bottom, since we're trying not to duplicate information. The article you're linking to is so without context, though, that this addition might be reasonable. I'm going to check with the CLI team to see what they think.

[Sharra-writes]

@kaviraj07 Okay, the CLI team does want it noted where the update command can be found, but this article is explicitly about installing for the first time, so the information on updates does belong at the bottom under "next steps." Something like, "For a list of commands for {% data variables.copilot.copilot_cli_short %}, including the command to update, see [AUTOTITLE](/copilot/reference/copilot-cli-reference/cli-command-reference)."

[kaviraj07]

@Sharra-writes Thanks for following up with the CLI team! I've moved the update info to Next steps with your suggested wording and removed the standalone section, so the article stays focused on first-time installation. Let me know if anything else needs changing.