Update memory.md

Minor updates to formatting.

Author: Tbkhi

src/memory.md

@@ -1,8 +1,8 @@
 # Memory Management in Rustc
 
-Rustc tries to be pretty careful how it manages memory. The compiler allocates
-_a lot_ of data structures throughout compilation, and if we are not careful,
-it will take a lot of time and space to do so.
+Generally `rustc` tries to be pretty careful how it manages memory. The
+compiler allocates _a lot_ of data structures throughout compilation, and if we
+are not careful, it will take a lot of time and space to do so.
 
 One of the main way the compiler manages this is using [arena]s and [interning].
 
@@ -11,52 +11,53 @@ One of the main way the compiler manages this is using [arena]s and [interning].
 
 ## Arenas and  Interning
 
-We create a LOT of data structures during compilation. For performance reasons,
-we allocate them from a global memory pool; they are each allocated once from a
-long-lived *arena*. This is called _arena allocation_. This system reduces
-allocations/deallocations of memory. It also allows for easy comparison of
-types for equality: for each interned type `X`, we implemented [`PartialEq for
-X`][peqimpl], so we can just compare pointers. The [`CtxtInterners`] type
-contains a bunch of maps of interned types and the arena itself.
+Since A LOT of data structures are created during compilation, for performance
+reasons, we allocate them from a global memory pool. Each are allocated once
+from a long-lived *arena*. This is called _arena allocation_. This system
+reduces allocations/deallocations of memory. It also allows for easy comparison
+of types for equality: for each interned type `X`, we implemented [`PartialEq`
+for X][peqimpl], so we can just compare pointers. The [`CtxtInterners`] type
+contains a bunch of maps of interned types and the `arena` itself.
 
 [peqimpl]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.Ty.html#implementations
 [`CtxtInterners`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.CtxtInterners.html#structfield.arena
 
 ### Example: `ty::TyKind`
 
-Taking the example of [`ty::TyKind`] which represents a type in the compiler (you
-can read more [here](./ty.md)).  Each time we want to construct a type, the
-compiler doesn’t naively allocate from the buffer.  Instead, we check if that
-type was already constructed. If it was, we just get the same pointer we had
-before, otherwise we make a fresh pointer. With this schema if we want to know
-if two types are the same, all we need to do is compare the pointers which is
-efficient. `TyKind` should never be constructed on the stack, and it would be unusable
-if done so.
-You always allocate them from this arena and you always intern them so they are
+Take [`ty::TyKind`] which represents a type in the compiler (you can read more
+[here](./ty.md)).  Each time we want to construct a type, the compiler doesn’t
+naively allocate from the buffer. Instead, we check if that type was already
+constructed. If it was, we just get the same pointer we had before, otherwise
+we make a fresh pointer. With this schema if we want to know if two types are
+the same, all we need to do is compare pointers, which is efficient. `TyKind`
+should never be constructed on the stack, and it would be unusable if done so.
+You always allocate them from this `arena` and you always intern them so they
+are
 unique.
 
-At the beginning of the compilation we make a buffer and each time we need to allocate a type we use
-some of this memory buffer. If we run out of space we get another one. The lifetime of that buffer
-is `'tcx`. Our types are tied to that lifetime, so when compilation finishes all the memory related
-to that buffer is freed and our `'tcx` references would be invalid.
+At the beginning of the compilation we make a buffer and each time we need to
+allocate a type we use some of this memory buffer. If we run out of space we
+get another one. The lifetime of that buffer is `'tcx`. Our types are tied to
+that lifetime, so when compilation finishes all the memory related to that
+buffer is freed and our `'tcx` references are invalidated.
 
 In addition to types, there are a number of other arena-allocated data structures that you can
 allocate, and which are found in this module. Here are a few examples:
 
 - [`GenericArgs`], allocated with `mk_args` – this will intern a slice of types, often used
-to specify the values to be substituted for generics args (e.g. `HashMap<i32, u32>` would be
-represented as a slice `&'tcx [tcx.types.i32, tcx.types.u32]`).
+  to specify the values to be substituted for generics args (e.g. `HashMap<i32, u32>` would be
+  represented as a slice `&'tcx [tcx.types.i32, tcx.types.u32]`).
 - [`TraitRef`], typically passed by value – a **trait reference** consists of a reference to a trait
   along with its various type parameters (including `Self`), like `i32: Display` (here, the def-id
   would reference the `Display` trait, and the args would contain `i32`). Note that `def-id` is
   defined and discussed in depth in the `AdtDef and DefId` section.
-- [`Predicate`] defines something the trait system has to prove (see `traits` module).
+- [`Predicate`] defines something the trait system has to prove (see [traits] module).
 
 [`GenericArgs`]: ./generic_arguments.html#GenericArgs
-[`TraitRef`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.TraitRef.html
 [`Predicate`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.Predicate.html
-
+[`TraitRef`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.TraitRef.html
 [`ty::TyKind`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/sty/type.TyKind.html
+[traits]: ./traits/resolution.md
 
 ## The tcx and how it uses lifetimes
 
@@ -78,7 +79,7 @@ the arenas, anyhow).
 ### A Note On Lifetimes
 
 The Rust compiler is a fairly large program containing lots of big data
-structures (e.g. the AST, HIR, and the type system) and as such, arenas and
+structures (e.g. the `AST`, `HIR`, and the type system) and as such, arenas and
 references are heavily relied upon to minimize unnecessary memory use. This
 manifests itself in the way people can plug into the compiler (i.e. the
 [driver](./rustc-driver.md)), preferring a "push"-style API (callbacks) instead