Add documentation to Matchers

Author: elenipapanik

ErrorHandler/Classes/Core/Matchers.swift

@@ -8,24 +8,50 @@
 
 import Foundation
 
+/**
+ An `ErrorMatcher` is an alternative to using `matches` closures when adding `ErrorActions` to an `ErrorHandler`. An `ErrorMatcher` is considered to match an error when it's `matches` function returns `true` for this error. `ErrorMatcher`s are used to match errors with the `ErrorHandler`'s `on(_ matcher: ErrorMatcher, do action: @escaping ErrorAction)` method.
+
+ `ErrorMatcher`s can be combined using || and && operators.
+ For example:
+
+ ```
+ let notConnectedMatcher = NSErrorMatcher(domain: NSURLErrorDomain, code: NSURLErrorNotConnectedToInternet)
+
+ let connectionLostMatcher = NSErrorMatcher(domain:   NSURLErrorDomain, code: NSURLErrorNetworkConnectionLost)
+
+ let offlineMatcher = notConnectedMatcher || connectionLostMatcher
+ ```
+ Error matchers have the additional benefit compared to `matches` closures that they describe matching logic in a way that can be more naturally reused. i.e. it is more natural in `Swift` to reuse Types than free functions and closures as the unit of composition in Swift is the type.
+ */
 public protocol ErrorMatcher {
+
+    /**
+     The `ErrorMatcher` is considered to match the error if this function returns true.
+     - Returns: `true` if the matcher matches the `error` otherwise `false`
+     */
     func matches(_ error: Error) -> Bool
 }
 
+/**
+ A generic `ErrorMatcher` over type `E` that `matches` an error if the error `is` `T`
+ */
 public class ErrorTypeMatcher<E: Error>: ErrorMatcher {
     public init() {}
     public func matches(_ error: Error) -> Bool {
         return error is E
     }
 }
 
+/**
+ An `ErrorMatcher` that wraps a `matches` closure
+ */
 public class ClosureErrorMatcher: ErrorMatcher {
     private let matches: (Error) -> Bool
-    
+
     public init(matches: @escaping (Error) -> Bool) {
         self.matches = matches
     }
-    
+
     public func matches(_ error: Error) -> Bool {
         return self.matches(error)
     }