added this as a third generic exercise

exercises/generics/generics3.rs

@@ -0,0 +1,31 @@
+// generics3.rs
+// Use your knowledge of generics to fix the `last_on_list` function signature.
+
+// Execute `rustlings hint generics3` or use the `hint` watch subcommand for a hint.
+
+// I AM NOT DONE
+
+fn last_on_list(list: &[&str]) -> &str {
+    list.last().unwrap()
+}
+
+fn main() {
+    // You can optionally experiment here.
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn store_str_on_list() {
+        let names_list = vec!["maria", "jacob", "kacper"];
+        let last = last_on_list(&names_list);
+    }
+
+    #[test]
+    fn store_numbers_on_list() {
+        let numbers_list = vec![1, 2, 3];
+        let last = last_on_list(&names_list);
+    }
+}

info.toml

@@ -684,6 +684,18 @@ Maybe we could update the explicit references to this data type somehow?
 If you are still stuck https://doc.rust-lang.org/stable/book/ch10-01-syntax.html#in-method-definitions
 """
 
+[[exercises]]
+name = "generics3"
+path = "exercises/generics/generics3.rs"
+mode = "test"
+hint = """
+Vectors in Rust use generics to create dynamically-sized arrays of any type.
+The last_on_list function takes a vector as an argument, but only accepts vectors that store the &str type.
+To allow the function to accept vectors that store any type, you can leverage your knowledge about generics.
+If you're unsure how to proceed, please refer to the Rust Book at:
+https://doc.rust-lang.org/book/ch10-01-syntax.html#in-function-definitions.
+"""
+
 # TRAITS
 
 [[exercises]]