Correct Synchronous Concurrency Talk Link (TextureGroup#698)

Fixes TextureGroup#697.

docs/_docs/synchronous-concurrency.md

@@ -12,7 +12,7 @@ By setting this property to YES, the main thread will be blocked until display h
 
 Using this option does not eliminate all of the performance advantages of Texture. Normally, a given node has been preloading and is almost done when it reaches the screen, so the blocking time is very short.  Even if the rangeTuningParameters are set to 0 this option outperforms UIKit.  While the main thread is waiting, all subnode display executes concurrently, thus synchronous concurrency.
 
-See the <a href="goo.gl/KJijuX">NSSpain 2015 talk video</a> for a visual walkthrough of this behavior.
+See the <a href="https://goo.gl/KJijuX">NSSpain 2015 talk video</a> for a visual walkthrough of this behavior.
 
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 <span class="language-toggle"><a data-lang="swift" class="swiftButton">Swift</a><a data-lang="objective-c" class = "active objcButton">Objective-C</a></span>