docs: clarify GitHub MCP setup for enterprise environments

Add language acknowledging users may already have GitHub MCP
configured or need to use company-approved configurations.

docs/how-to/installation/claude-desktop-github.md

@@ -13,7 +13,9 @@ Use BMAD agents directly in Claude Desktop by reading agent files from GitHub. P
 
 ## Step 1: Configure GitHub MCP
 
-Open Claude Desktop settings and add the GitHub MCP server:
+If you don't already have GitHub MCP configured, follow these steps. If your company has an approved GitHub MCP configuration, use that instead.
+
+**To add GitHub MCP manually:**
 
 1. Go to **Settings** → **Developer** → **Model Context Protocol**
 2. Add this configuration:

src/modules/bmm/agents/po.agent.yaml

@@ -208,7 +208,10 @@ agent:
 
         Both Claude Desktop and Claude Code need GitHub MCP for team features.
 
-        **To add GitHub MCP:**
+        If you already have GitHub MCP configured, skip to Step 2.
+        If your company has an approved GitHub MCP setup, use that instead.
+
+        **To add GitHub MCP manually:**
         1. Open Settings (Cmd/Ctrl + ,)
         2. Go to "Developer" → "Model Context Protocol"
         3. Add the GitHub MCP server: