minor cleanup to JS docs

docs/js/variables.md

@@ -1,6 +1,6 @@
 # Variable Declarations
 
-Declaring a variable should be done using the ``let`` keyworld:
+Declaring a variable should be done using the ``let`` keyword:
 
 ```typescript
 let a = 10;
@@ -24,6 +24,10 @@ let a = 10;
 
 The key difference is not in the syntax, but in the semantics, which we'll now dive into.
 
+### ~hint
+### Use `let` instead of `var` to introduce a new variable.
+### ~
+
 ## Block-scoping
 
 When a variable is declared using `let`, it uses what some call *lexical-scoping* or *block-scoping*.