docs(internal): update CONTRIBUTING.md to recommend unminified build (#9941)

Update the CLI building documentation to recommend using 'pnpm fern:build:unminified' for local development and debugging. This provides a better developer experience with readable variable names and code structure while still using production environment variables.

The minified build ('pnpm fern:build') is still available for those who need it.

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
Co-authored-by: Deep Singhvi <[email protected]>

Author: devin-ai-integration[bot]

CONTRIBUTING.md

@@ -112,8 +112,9 @@ The Fern CLI lives in a directory called [cli](./packages/cli/cli/) and the entr
 
 ### Building the CLI from source
 
-For testing purposes, you can build a local version of the CLI by running `pnpm fern:build`. This compiles and builds a CLI
-that communicates with our production cloud environment.
+For local development and debugging, you can build an unminified version of the CLI by running `pnpm fern:build:unminified`. This compiles and builds a CLI that communicates with our production cloud environment but preserves readable code for easier debugging.
+
+If you need a minified production build instead, you can run `pnpm fern:build`.
 
 The CLI is outputted to `packages/cli/cli/dist/prod/cli.cjs`.