* update to the latest alpine version
* support independant git account name from git-server repository location
* update documentation

… well

The following .gitconfig will replace https with ssh.
```
[url "ssh://[email protected]"]
	insteadOf = https://github.com/
```

This will change the behaviour of `git clone` from
```
git clone https://github.com/fra123k/git-server-docker
```
to
```
git clone [email protected]:fr123k/git-servert-docker
```

This correct but it results in ssh access denied because the local git
server container only provide the `git` user and not the `fr123k` user
ssh access.

This solved by setting up account user of the github repository.
At the moment only one account user is supported.