Clarify rate limit error message and actions

Updated the rate limit error message for clarity and added guidance on what to do if rate limited. Applies to behavior of GitHub Copilot Chat v0.45.1

Author: kudosscience

content/copilot/how-tos/troubleshoot-copilot/troubleshoot-common-issues.md

@@ -71,7 +71,7 @@ Most people see rate limiting for select models, due to limited capacity.
 
 Service-level request rate limits ensure high service quality for all {% data variables.product.prodname_copilot_short %}  users and should not affect typical or even deeply engaged {% data variables.product.prodname_copilot_short %} usage. We are aware of some use cases that are affected by it. {% data variables.product.github %} is iterating on {% data variables.product.prodname_copilot_short %}’s rate-limiting heuristics to ensure it doesn’t block legitimate use cases.
 
-If you are rate limited, the error message will contain the suggested retry time for a successful request. For more information about alternative actions you can take while your limit resets, see [AUTOTITLE](/copilot/concepts/usage-limits#what-to-do-if-you-hit-a-limit).
+If you are rate limited, the error message will read: "You've hit your session rate limit. Please upgrade your plan or wait a moment for your limit to reset.". For more information about alternative actions you can take while your limit resets, see [AUTOTITLE](/copilot/concepts/usage-limits#what-to-do-if-you-hit-a-limit).
 
 In case you experience repeated rate limiting in {% data variables.product.prodname_copilot_short %} contact {% data variables.contact.contact_support_page %}.