[ru] chapter 2: Incorporate changes from commits 716e192 and aa83065

"Add --word-diff option description"
[ru] chapter 4: Incorporate changes from commit 192518071.

"Updated explanation of ssh protocols."
[ja] Improve translation of chapter 9
[ja] Correct a description of .git/info in chapter 9
[ja] Fix a typo in chapter 9
[ru] chapter 2: Translate figures.
[ru] Update chapter 1

Fix some punctuation problems.
Merge pull request #438 from rc5hack/master

[ru] Update chapter 1
Merge pull request #436 from uasi/ja-chapter9

[ja] Improve chapter 9
Merge pull request #440 from gibas/spelling-fixes

spelling fixes, translation improvements
Merge pull request #439 from GArik/RU

[ru] Sync translation with the original and translate one more figure
[ru] Update chapter 4

Fix some punctuation problems.
Merge pull request #441 from rc5hack/master

[ru] Update chapter 4
[en] Update chapter 4

Wikipedia link changes too often, so replace it with kernel.org.
Merge pull request #442 from rc5hack/en

[en] Update chapter 4