magit: Fix type of `magit-repo-dirs'.

It's a list of directories.
Merge pull request #1591 from ruediger/type-fix

magit: Fix type of `magit-repo-dirs'.
Fix shortcuts in documentation

The correct keyboard shortcuts to retrieve commit messages after a
canceled commit are `M-p' and `M-n', not `M-p' and `M-n' as previously stated.
Merge pull request #1616 from leafac/master

Fix shortcuts in documentation
Fix branch mark in documentation

The current branch is marked by `*', not by a `#'.
Merge pull request #1617 from leafac/fix-branch-mark

Fix branch mark in documentation
magit-status-internal: new forward compatibility alias

for `magit-status'.
AUTHORS.md: update list of contributors