Add DocC documentation

Sources/Logging OSLog/Logging OSLog.swift

@@ -8,6 +8,22 @@ public struct LoggingOSLog: LogHandler {
 	public var metadataProvider: Logging.Logger.MetadataProvider?
 	private let oslogger: os.Logger
 
+	/**
+		Initializer that may be passed directly to 
+		[LoggingSystem.bootstrap](https://swiftpackageindex.com/apple/swift-log/1.10.1/documentation/logging/loggingsystem/bootstrap(_:)).
+
+		- Parameter label: Example: com.example.sometool.MailProcessing
+						   A reverse domain style identifier. The part up until the
+						   last dot is used as the subsystem and the part after the
+						   last dot is used as the category of the unified logging
+						   message.
+						   After the last dot spaces may be used to separate words.
+						   If you want to use the application bundle identifier as the
+						   subsystem, use a value without any dot and the whole value
+						   will be mapped as the category of the unified logging system and
+						   the subsystem is either the bundle identifier - if any - or
+						   the string "SwiftLogToOsLog".
+	 */
 	public init(label: String) {
 		let lastDotPosition = label.lastIndex(of: ".") ?? label.startIndex
 		let frontPart = label.prefix(upTo: lastDotPosition)
@@ -20,6 +36,16 @@ public struct LoggingOSLog: LogHandler {
 		self.init(subsystem: String(frontPart), category: String(backPart))
 	}
 
+	/**
+		This Initializer may not be passed directly to
+		[LoggingSystem.bootstrap](https://swiftpackageindex.com/apple/swift-log/1.10.1/documentation/logging/loggingsystem/bootstrap(_:)).
+		It must be wrapped beforehand, but allows for direct assignment of subsystem and
+		category parameters of [OSLog](https://developer.apple.com/documentation/oslog).
+
+		- Parameters:
+			- subsystem: See the [Apple documentation](https://developer.apple.com/documentation/os/generating-log-messages-from-your-code#:~:text=The%20subsystem%20string,for%20each%20subsystem%20string.) for this parameter.
+			- category: See the [Apple documentation](https://developer.apple.com/documentation/os/generating-log-messages-from-your-code#:~:text=The%20category%20string,for%20these%20strings.) for this parameter.
+	 */
 	public init(
 		subsystem: String = Bundle.main.bundleIdentifier ?? "SwiftLogToOsLog",
 		category: String,
@@ -29,11 +55,20 @@ public struct LoggingOSLog: LogHandler {
 		self.logLevel = logLevel
 	}
 
+	/**
+		This Initializer may not be passed directly to
+		[LoggingSystem.bootstrap](https://swiftpackageindex.com/apple/swift-log/1.10.1/documentation/logging/loggingsystem/bootstrap(_:)).
+		Use it, when you've already a fully configured [os.Logger](https://developer.apple.com/documentation/os/logging)
+		instance.
+	 */
 	public init(oslog: os.Logger, logLevel: Logging.Logger.Level = .debug) {
 		self.oslogger = oslog
 		self.logLevel = logLevel
 	}
 
+	/**
+		This function is called by [SwiftLog](https://github.com/apple/swift-log).
+	 */
 	public func log(
 		level: Logging.Logger.Level,
 		message: Logging.Logger.Message,
@@ -50,6 +85,9 @@ public struct LoggingOSLog: LogHandler {
 		self.oslogger.log(level: OSLogType.from(loggerLevel: level), "\(message)")
 	}
 
+	/**
+		Use subscripts on struct instances, to add metadata for all future log messages.
+	 */
 	public subscript(metadataKey metadataKey: String) -> Logging.Logger.Metadata.Value? {
 		get {
 			return self.metadata[metadataKey]
@@ -72,4 +110,4 @@ public struct LoggingOSLog: LogHandler {
 		guard !metadata.isEmpty else { return nil }
 		return metadata.map { "\($0) = \($1)" }.joined(separator: separator)
 	}
-}
+}