Add short description how to configure an abapGit Project for abaplint

[gregorwolf]

As https://github.com/apps/abaplint and also https://abaplint.org do not provide any information what are the prerequisites to setup a abapGit Project for abaplint I found it out by using one of the existing examples. But I think we could make the live of users easier by providing a guide. This should also include how to add a badge to your project.

[larshp]

agree

note that badges doesnt really work anymore, I just changed it to show ok for everything