fix comment error on isFeatureEnabled and getEnabledFeatures (#275)

Author: jaeopt

Sources/Optimizely/OptimizelyClient.swift

@@ -344,7 +344,6 @@ open class OptimizelyClient: NSObject {
     ///   - userId: The user ID to be used for bucketing.
     ///   - attributes: The user's attributes.
     /// - Returns: true if feature is enabled, false otherwise.
-    /// - Throws: `OptimizelyError` if feature parameter is not valid
     public func isFeatureEnabled(featureKey: String,
                                  userId: String,
                                  attributes: OptimizelyAttributes? = nil) -> Bool {
@@ -565,7 +564,6 @@ open class OptimizelyClient: NSObject {
     ///   - userId: The user ID to be used for bucketing.
     ///   - attributes: The user's attributes.
     /// - Returns: Array of feature keys that are enabled for the user.
-    /// - Throws: `OptimizelyError` if feature parameter is not valid
     public func getEnabledFeatures(userId: String,
                                    attributes: OptimizelyAttributes? = nil) -> [String] {