Add missing word (grammar)

A `static` variable declared globally can called -> A `static` variable declared globally can be called
Fixes accidental “not” in sentence regarding avoiding deadlock
“..so it is critical to implement this correctly so as to not avoid deadlock..” -> “..so it is critical to implement this correctly so as to avoid deadlock..”
Merge pull request #63 from sampage/NSOperation-accidental-word-typo-fix

Fixes accidental “not” in sentence regarding avoiding deadlock
Merge pull request #62 from douglashill/master

Fix ‘useInfo’ typo in NSNotification & NSNotificationCenter.
Merge pull request #57 from dkasper/patch-2

Add missing word (grammar)
Insert missing apostrophe
Insert missing apostrophe
Insert missing "is"
Adding Multipeer Connectivity article
Fix typos
Adding id to table
Copy edit
Merge pull request #68 from oleksii-taran/fix_typo

Fix typos
Merge pull request #67 from mikeabdullah/patch-2

Minor typo fixes
Added mention of the C99 _Pragma operator, which can be used in macros
Changed reference to pragma in the __attributes__ article
Adding article about UIApplicationDelegate launchOptions
Update article about launch options

Add additional space between words.
Merge pull request #74 from twealm/master

Update article about launch options
Fixing markup errors