feat(macros): add hint comments

exercises/macros/macros1.rs

@@ -1,5 +1,5 @@
 // macros1.rs
-// Make me compile! Execute `rustlings hint macros1` for hints :)
+// Execute `rustlings hint macros1` or use the `hint` watch subcommand for a hint.
 
 // I AM NOT DONE
 

exercises/macros/macros2.rs

@@ -1,5 +1,5 @@
 // macros2.rs
-// Make me compile! Execute `rustlings hint macros2` for hints :)
+// Execute `rustlings hint macros2` or use the `hint` watch subcommand for a hint.
 
 // I AM NOT DONE
 

exercises/macros/macros3.rs

@@ -1,6 +1,6 @@
 // macros3.rs
 // Make me compile, without taking the macro out of the module!
-// Execute `rustlings hint macros3` for hints :)
+// Execute `rustlings hint macros3` or use the `hint` watch subcommand for a hint.
 
 // I AM NOT DONE
 

exercises/macros/macros4.rs

@@ -1,5 +1,5 @@
 // macros4.rs
-// Make me compile! Execute `rustlings hint macros4` for hints :)
+// Execute `rustlings hint macros4` or use the `hint` watch subcommand for a hint.
 
 // I AM NOT DONE
 

info.toml

@@ -958,7 +958,12 @@ mode = "compile"
 hint = """
 You only need to add a single character to make this compile.
 The way macros are written, it wants to see something between each
-"macro arm", so it can separate them."""
+"macro arm", so it can separate them.
+
+That's all the macro exercises we have in here, but it's barely even
+scratching the surface of what you can do with Rust's macros. For a more
+thorough introduction, you can have a read through the little book of Rust
+macros: https://veykril.github.io/tlborm/"""
 
 # TEST 4