Recommend using HTTPS instead of SSH (#43)

Author: jminor

README.md

@@ -61,7 +61,7 @@ from the command line easily as well:
 ====================
 
 Use the Package Manager in Xcode and bring in
-  `git@github.com:OpenTimelineIO/OpenTimelineIO-Swift-Bindings.git`
+  `https://github.com/OpenTimelineIO/OpenTimelineIO-Swift-Bindings.git`
 
 You should see a choice of two C++ products that can be added to your workspace;
 for Swift development, choose the third product named `OpenTimelineIO`.