Updater: Add code documentation Markdown file

Add docs/autoupdate_overview.md which gives an overview of the update
process, and comments pointing to it in autoupdate related files.

Source/Core/MacUpdater/AppDelegate.mm

@@ -10,13 +10,16 @@
 #include <string>
 #include <vector>
 
+// Refer to docs/autoupdate_overview.md for a detailed overview of the autoupdate process
+
 @interface AppDelegate ()
 
 @end
 
 @implementation AppDelegate
 
-- (void)applicationDidFinishLaunching:(NSNotification*)aNotification {
+- (void)applicationDidFinishLaunching:(NSNotification*)aNotification
+{
   NSArray* arguments = [[NSProcessInfo processInfo] arguments];
 
   __block std::vector<std::string> args;
@@ -32,7 +35,8 @@
   });
 }
 
-- (void)applicationWillTerminate:(NSNotification*)aNotification {
+- (void)applicationWillTerminate:(NSNotification*)aNotification
+{
 }
 
 @end

Source/Core/MacUpdater/main.m

@@ -4,6 +4,8 @@
 
 #include <Cocoa/Cocoa.h>
 
+// Refer to docs/autoupdate_overview.md for a detailed overview of the autoupdate process
+
 int main(int argc, const char** argv)
 {
   if (argc == 1)