docs: clarify region-mismatch consequence in re-use Foundry note

Deploy may fail at provisioning time for unsupported gpt-5.1 region, or appear to succeed but break at runtime when Content Understanding GA is unavailable in the existing Foundry's region.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Harsh-Microsoft

docs/re-use-foundry-project.md

@@ -7,7 +7,7 @@ To configure your environment to use an existing Azure AI Foundry Project, follo
 >
 > The existing Foundry project must reside in a region that supports **both** the GPT model deployed by this accelerator (default `gpt-5.1` with `GlobalStandard` deployment type) **and** Azure AI Content Understanding (GA).<br>
 > Supported regions: `australiaeast`, `eastus`, `eastus2`, `northcentralus`, `southcentralus`, `swedencentral`, `switzerlandnorth`, `westeurope`, `westus`, `westus2`, `westus3`.<br>
-> If the existing project is in a different region, deployment will fail.
+> If the existing project is in a different region, deployment will fail or the application will not work correctly.
 
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 ### 1. Go to Azure Portal