add prompts

Xcode/PlaygroundAction.txt

@@ -0,0 +1,20 @@
+The user is curently inside this file: {{filename}}
+The contents are below:
+```swift:{{filename}}
+{{filecontent}}
+```
+
+The user has selected the following code from that file:
+```swift
+{{selected}}
+```
+
+The user has asked:
+
+Provide a brief example on how to use `{{selected}}`.
+
+- Respond only with a single code block.
+- Don't use comments. 
+- Don't use print statements. 
+- Don't import any additional modules.
+