[de] Fix typos in section 6
Fix wrong comma
[de] Connect compound nouns with dash, more minor fixes
[de] Connect compound nouns with dash
[de] Use "Branch master" instead of "Master-Branch"

- master is a special term in Git terminology
- It is used in other sections in the exact same manner
[de] Use correct plural Repositorys instead of Repositories
[de] Review paragraphs marked with "xxx" and fix them
[de] Numbers less than twelve are written-out
[de] Fix typo
[de] Update status of chapter 6 and add some git specific terms
Merge branch 'issue-8-enhance-section-6-4-to-6-8'
Merge pull request #9 from jublonet/issue-8-enhance-section-6-4-to-6-8

[de] Fix typos in section 6
Merge branch 'next'
Merge pull request #636 from progit-de/next

[de] Chapter 6: Fix of several typos and result of review by Fernsehkind & jublo