reorder glossary

Author: nikomatsakis

Diff for: src/glossary.md

@@ -15,10 +15,10 @@ cx                      |  we tend to use "cx" as an abbrevation for context. Se
 DAG                     |  a directed acyclic graph is used during compilation to keep track of dependencies between queries. ([see more](incremental-compilation.html))
 data-flow analysis      |  a static analysis that figures out what properties are true at each point in the control-flow of a program; see [the background chapter for more](./background.html#dataflow)  
 DefId                   |  an index identifying a definition (see `librustc/hir/def_id.rs`). Uniquely identifies a `DefPath`.
+free variable           |  a "free variable" is one that is not bound within an expression or term; see [the background chapter for more](./background.html#free-vs-bound)
 HIR                     |  the High-level IR, created by lowering and desugaring the AST ([see more](hir.html))
 HirId                   |  identifies a particular node in the HIR by combining a def-id with an "intra-definition offset".
 HIR Map                 |  The HIR map, accessible via tcx.hir, allows you to quickly navigate the HIR and convert between various forms of identifiers.
-free variable           |  a "free variable" is one that is not bound within an expression or term; see [the background chapter for more](./background.html#free-vs-bound)
 'gcx                    |  the lifetime of the global arena ([see more](ty.html))
 generics                |  the set of generic type parameters defined on a type or item
 ICE                     |  internal compiler error. When the compiler crashes.