[pl] translation of section 9.6
Merge pull request #467 from gibas/09-git-internals

[pl] translation of section 9.6
[pl] translated section 9.7
Correct Typo
Correct typo 'commited' to 'committed'. Burnishing is going on!
Merge pull request #469 from gibas/09-git-internals

[pl] translated section 9.7
[pl] spelling fixes
[pl] s/email/e-mail/g
Merge pull request #471 from Rabierre/master

Correct Typo
Merge pull request #470 from gibas/spelling-fixes

[pl] Spelling fixes