Fix expired playground link

Author: erikhatcher

docs/60_Relevancy/8_Exercises.mdx

@@ -2,7 +2,7 @@
 
 ## project the score
 
-<Playground url="https://search-playground.mongodb.com/tools/code-sandbox/snapshots/67d2ef3c808223b17a90bd7a">🔗 Playground link: score not projected</Playground>
+<Playground url="https://search-playground.mongodb.com/tools/code-sandbox/snapshots/6984fef8968279618745dce3">🔗 Playground link: score not projected</Playground>
 
 Fix this Playground so that the `score` being projected is the relevancy score Atlas Search uses for default sorting.