Enhance documentation for initial setup

Being struggling for 2 days in building the repository, I would suggest to enhance install documentation.

Main issue is repetitive "fetch-pack: unexpected disconnect while reading sideband packet" during git clone.
Either to load initial https://github.com/juliusknorr/nextcloud-docker-dev. Or when running bootstrap script.

Documentation should make it more clear that the steps:
git config --global core.compression 0
git clone --depth 1 https://github.com/juliusknorr/nextcloud-docker-dev
git fetch --unshallow

Recommand to make backup copy nextcloud-docker-dev
cp -r nextcloud-docker-dev nextcloud-docker-copy
before to run bootstrap script
This allow to restart without struggling again to download repository in case of failure during execution of bootstrap scrip.

Also the way to edit bootstrat script to make git clone safer. Or provide an alternate bootstrap script to make git clone safe

Start by locating the install documentation and the bootstrap script mentioned in the issue, then review how repository cloning currently works. Document the safer clone and backup steps, or clarify the bootstrap alternative, and verify that a failed setup can be restarted without downloading the repository again.