highlight the existence of git 'tree' object type to distinguish it (e.g. from file system tree)
[ja] Apply 1f57d57a48144a978d9f8b52c38550804297ee1d
Packfile 설명의 해시코드 오타 수정
[ko] chapter 9: fix a trivial typo

addressble -> addressable
fixed a typo.
[ko] chapter 6: fix a word
[ko] Up to date
[ko] Proofreading ch. 01
Merge branch '01' into ko

* 01:
  [ko] Proofreading ch. 01
  [ko] Up to date
[ko] Up to date, chapter2
[ko] Proofreading ch. 02
[de] Improve german translation of chapter 6.3 (Stashing)
Merge branch '02' into ko

* 02:
  [ko] Proofreading ch. 02
  [ko] Up to date, chapter2
[ko] Up to date, chapter3
[ko] Proofreading ch. 03
[ko] fix mis-trasnlation
Merge branch '03' into ko

* 03:
  [ko] fix mis-trasnlation
  [ko] Proofreading ch. 03
  [ko] Up to date, chapter3
[ko] Up to date, chapter4
[ko] Proofreading ch. 04
[ko] Clarify the meaning of a sentence.