update group example link to read only (#109)

Author: srachmiletter

README.md

@@ -198,7 +198,7 @@ val newDataset: Dataset<Pair<TypeA, TypeB>> = dataset.selectTyped(col(YourClass:
 
 We had to implement the functions `reduceGroups` and `reduce` for Kotlin separately as `reduceGroupsK` and `reduceK` respectively, because otherwise it caused resolution ambiguity between Kotlin, Scala and Java APIs, which was quite hard to solve.
 
-We have a special example of work with this function in the [Groups example](https://github.com/JetBrains/kotlin-spark-api/edit/main/examples/src/main/kotlin/org/jetbrains/kotlinx/spark/examples/Group.kt).
+We have a special example of work with this function in the [Groups example](https://github.com/JetBrains/kotlin-spark-api/blob/main/examples/src/main/kotlin/org/jetbrains/kotlinx/spark/examples/Group.kt).
 
 
 ## Examples