调整了开头的一些翻译
Update 21Protocols.md

90%
Merge pull request #2 from CocoaChina-editors/master

merge to edit
Update 21Protocols.md

100%
Update 21Protocols.md
Update 21Protocols.md
add A.3-10

add A.3-10
add A.3-9

add A.3-9
add A.3-8

add A.3-8
add A.3-5

add A.3-5
add A.3-6

add A.3-6
add A.3-2

add A.3-2
Merge branch 'master' of https://github.com/CocoaChina-editors/Welcome-to-Swift
add the unfinished chapter

add the unfinished chapter
更新目录

更新目录
同步更新 A.2-1

同步更新 A.2-1
同步 A.2-3

同步 A.2-3
update A.2-8

update A.2-8
校对内容
Update 08Patterns.md