Adds attribution for SVG source

adds source for TC SVG source (wikimedia) and notes that the angle of
the “airplane” in the turn coordinator would show the opposite angle of
the attitude indicator, as the AI mirrors what you see out the window,
and the TC airplane mirrors what the wings are doing.

example.html

@@ -98,7 +98,8 @@ <h2>Realtime indicators</h2>
 </div>
 
 <footer>
- jQuery Flight Indicator plugin by Sébastien Matton - License GPLv3
+ jQuery Flight Indicator plugin by Sébastien Matton - License GPLv3<br/>
+ <a title="By Mysid [CC-BY-SA-3.0 (http:https://creativecommons.org/licenses/by-sa/3.0) or GFDL (http:https://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons" href="http:https://commons.wikimedia.org/wiki/File%3ATurn_coordinator.svg">Turn Coordinator SVG from Wikimedia Commons</a>
 </footer>
 
 <!-- Syntax color -->
@@ -137,8 +138,8 @@ <h2>Realtime indicators</h2>
  altimeter.setPressure(1000+3*Math.sin(increment/50));
  increment++;
 
- // TC update
- turn_coordinator.setTurn(30*Math.sin(increment/10));
+ // TC update - note that the TC appears opposite the angle of the attitude indicator, as it mirrors the actual wing up/down position
+ turn_coordinator.setTurn((30*Math.sin(increment/10))*-1);
 
  // Heading update
  heading.setHeading(increment);