Apply 1cfb0503 to all languages

A stable reference page which is not outdated for git hosting is
quite difficult to find. For the moment, just point to the one
on kernel.org.
speling fixes, added blank line between polish and oryginal text
small fix in section name
Add \usepackage{longtable} to fix 'Environment longtable undefined' problem with 'makepdfs zh'
Merge pull request #447 from gibas/spelling-fixes

[pl] small fix in section name in chapter 3
Merge pull request #446 from gibas/05-distributed-git

[pl] spelling fixes, add blank line between polish and original text
Merge pull request #448 from JulH/master

add '\usepackage{longtable}' to fix 'problem Environment longtable undefined'
Merge pull request #445 from progit/git_hosting

Apply 1cfb0503 to all languages
Merge branch 'progit/master' into ja