Next.js app configuration (#3516)

Be more explicit about what to do with the configuration of the app.

Author: iker-barriocanal

src/platforms/javascript/guides/nextjs/manual-setup.mdx

@@ -88,7 +88,10 @@ Also keep in mind, by default we disable source map upload in `dev` mode when ru
 
 ## Configure sentry-cli
 
-Under the hood, the `SentryWebpackPlugin` uses `sentry-cli`, which can be configured in one of two ways - using a properties file, or with environment variables - both of which are discussed below. For full details, see [the CLI configuration docs](https://docs.sentry.io/product/cli/configuration/). (If you choose to combine the two approaches, the environment variables will take precedence over values set in the properties file.)
+The `SentryWebpackPlugin` uses `sentry-cli`, which can be configured in one of two ways - using a properties file, or with environment variables - both of which are discussed below. For full details, see [the CLI configuration docs](https://docs.sentry.io/product/cli/configuration/).
+
+If you choose to combine the two approaches, the environment variables will take precedence over values set in the properties file.
+You can add the properties file to your VCS, excluding any sensitive data (like tokens), and add it to the environment variables.
 
 ### Properties File