message: More improvements to variable docs
diff: @@ -23,8 +23,8 @@ use std::fmt;
  type RawVar = u16;
  /// A [de Bruijn index], which represents a variable counting the number of
  -/// binders between a variable occurrence and its associated binder. For
  -/// example:
  +/// binders between a variable occurrence and the binder that introduced the
  +/// variable. For example:
  ///
  /// | Representation | Example (S combinator) |
  /// | ----------------- | ----------------------- |
  @@ -68,7 +68,7 @@ pub fn local_vars() -> impl Iterator<Item = LocalVar> {
  }
  /// A de Bruijn level, which represents a variable by counting the number of
  -/// binders between the variable's associated binder and the start of the
  +/// binders between the binder that introduced the variable and the start of the
  /// environment. For example:
  ///
  /// | Representation | Example (S combinator) |
  