Updating Instruction

Do not edit net.retrodeck.mame.yml nor manifest-header.yml:

These files are automatically generated by automation_tools/update_mame_manifest.sh.

manifest-header.yml is generated from the RetroDECK manifest itself, mind that:

• any changes to net.retrodeck.mame.yml will be discarded.
• any changes to manifest-header.yml will be discarded.

Then manifest-header.yml + the editable mame-module.yml are combined into net.retrodeck.mame.yml.

So please update mame-module.yml only.