mention at least 128GB of free disk space early on

guides/advanced/building-sytems.md

@@ -19,6 +19,7 @@ The `nerves_systems` build process only works on **Linux** systems with `x86_64`
   - **Native Linux Machine**: Best for performance and simplicity.
   - **macOS Users**: Install a Linux VM (e.g., via [UTM](https://mac.getutm.app)) to create an Ubuntu environment.
   - **Windows Users**: Use [WSL2](https://learn.microsoft.com/en-us/windows/wsl/install) with an Ubuntu distribution.
+- At least **128GB of free disk space**: Building Nerves systems can require significant disk space, depending on the components included in the system.
 
 ### Linux Environment Requirements
 
@@ -134,8 +135,6 @@ These steps are automated using the `ns.build` Mix task.
    mix ns.build
    ```
 
-   Depending on your system’s resources and the number of systems configured, this process may take some time. Ensure your machine has sufficient disk space (128 GB or more) and RAM.
-
 2. **Inspect the Output**
    Once the build completes, each system’s output will be located in its respective directory within the `o/` folder. For example: