Fix dead links (rust-lang#1988)

* fix dead links in memory.md

* fix dead links in ty_module/generic_arguments.md

* Update src/memory.md

use .md instead of .html for self-links

Co-authored-by: Noah Lev <[email protected]>

---------

Co-authored-by: Noah Lev <[email protected]>

Author: hycinth22

Diff for: src/memory.md

@@ -52,8 +52,8 @@ represented as a slice `&'tcx [tcx.types.i32, tcx.types.u32]`).
   defined and discussed in depth in the `AdtDef and DefId` section.
 - [`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
+[`GenericArgs`]: ./ty_module/generic_arguments.md#the-genericargs-type
+[`TraitRef`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/type.TraitRef.html
 [`Predicate`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.Predicate.html
 
 [`ty::TyKind`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/sty/type.TyKind.html

Diff for: src/ty_module/generic_arguments.md

@@ -37,7 +37,7 @@ for the generic parameters.  In our example of `MyStruct<u32>`, we would end up
 ### **`AdtDef` and `DefId`**
 
 For every type defined in the source code, there is a unique `DefId` (see [this
-chapter](hir.md#identifiers-in-the-hir)). This includes ADTs and generics. In the `MyStruct<T>`
+chapter](../hir.md#identifiers-in-the-hir)). This includes ADTs and generics. In the `MyStruct<T>`
 definition we gave above, there are two `DefId`s: one for `MyStruct` and one for `T`.  Notice that
 the code above does not generate a new `DefId` for `u32` because it is not defined in that code (it
 is only referenced).
@@ -111,7 +111,7 @@ fn deal_with_generic_arg<'tcx>(generic_arg: GenericArg<'tcx>) -> GenericArg<'tcx
 
 [list]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.List.html
 [`GenericArg`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.GenericArg.html
-[`GenericArgKind`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/enum.GenericArgKind.html
+[`GenericArgKind`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/type.GenericArgKind.html
 [`GenericArgs`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/type.GenericArgs.html
 
 So pulling it all together: