docs: maintain consistency on variable used on client config examples

Author: enriquegh

docs/api/mcp/index.mdx

@@ -79,11 +79,11 @@ You can add the Sourcegraph MCP server to [Amp](https://ampcode.com) in two ways
 Run the following command in your terminal:
 
 ```bash
-amp mcp add sourcegraph --header "Authorization=token $SRC_ACCESS_TOKEN" https://sourcegraph.sourcegraph.com/.api/mcp/v1
+amp mcp add sourcegraph --header "Authorization=token YOUR_ACCESS_TOKEN" https://sourcegraph.sourcegraph.com/.api/mcp/v1
 ```
 
 <Callout type="info">
-  Replace `sourcegraph.sourcegraph.com` with your Sourcegraph instance URL and set `$SRC_ACCESS_TOKEN` environment variable to your access token.
+  Replace `sourcegraph.sourcegraph.com` with your Sourcegraph instance URL and set `YOUR_ACCESS_TOKEN` environment variable to your access token.
 </Callout>
 
 ### Claude Code