feat(modules): update exercises, add modules3 (#822)

Co-authored-by: diannasoriel <mokou@fastmail.com>

info.toml

@@ -362,11 +362,19 @@ name = "modules2"
 path = "exercises/modules/modules2.rs"
 mode = "compile"
 hint = """
-The delicious_snacks module is trying to present an external
-interface (the `fruit` and `veggie` constants) that is different than
-its internal structure (the `fruits` and `veggies` modules and
-associated constants). It's almost there except for one keyword missing for
-each constant."""
+The delicious_snacks module is trying to present an external interface that is 
+different than its internal structure (the `fruits` and `veggies` modules and
+associated constants). Complete the `use` statemants to fit the uses in main and
+find the one keyword missing for both constants."""
+
+[[exercises]]
+name = "modules3"
+path = "exercises/modules/modules3.rs"
+mode = "compile"
+hint = """
+UNIX_EPOCH and SystemTime are declared in the std::time module. Add a use statement
+for these two to bring them into scope. You can use nested paths or the glob
+operator to bring these two in using only one line."""
 
 # COLLECTIONS