Update some links

Author: JohnTitor

src/borrow_check/region_inference.md

@@ -78,13 +78,12 @@ The value of a region can be thought of as a **set**. This set contains all
 points in the MIR where the region is valid along with any regions that are
 outlived by this region (e.g. if `'a: 'b`, then `end('b)` is in the set for
 `'a`); we call the domain of this set a `RegionElement`. In the code, the value
-for all regions is maintained in [the
-`rustc_mir::borrow_check::nll::region_infer` module][ri]. For each region we
-maintain a set storing what elements are present in its value (to make this
+for all regions is maintained in [the `rustc_borrowck::region_infer` module][ri].
+For each region we maintain a set storing what elements are present in its value (to make this
 efficient, we give each kind of element an index, the `RegionElementIndex`, and
 use sparse bitsets).
 
-[ri]: https://github.com/rust-lang/rust/tree/master/compiler/rustc_mir/src/borrow_check/region_infer/
+[ri]: https://github.com/rust-lang/rust/tree/master/compiler/rustc_borrowck/src/region_infer
 
 The kinds of region elements are as follows:
 

src/contributing.md

@@ -67,8 +67,8 @@ where contributors push changes to their personal fork and create pull requests
 bring those changes into the source repository. We have more info about how to use git
 when contributing to Rust under [the git section](./git.md).
 
-[about-pull-requests]: https://help.github.com/articles/about-pull-requests/
-[development-models]: https://help.github.com/articles/about-collaborative-development-models/
+[about-pull-requests]: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/about-pull-requests
+[development-models]: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/getting-started/about-collaborative-development-models#fork-and-pull-model
 
 ### r?
 
@@ -177,7 +177,7 @@ particularly during rebasing, citing the issue number in the commit can "spam"
 the issue in question.
 
 [labeling]: ./rustbot.md#issue-relabeling
-[closing-keywords]: https://help.github.com/en/articles/closing-issues-using-keywords
+[closing-keywords]: https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue
 
 ### External Dependencies (subtree)
 

src/git.md

@@ -18,7 +18,7 @@ more in depth [book from Git].
 
 [book from Git]: https://git-scm.com/book/en/v2/
 [atlassian-git]: https://www.atlassian.com/git/tutorials/what-is-version-control
-[documentation]: https://docs.github.com/en/github/getting-started-with-github/set-up-git
+[documentation]: https://docs.github.com/en/get-started/quickstart/set-up-git
 [guides]: https://guides.github.com/introduction/git-handbook/
 
 ## Prerequisites

src/query.md

@@ -37,7 +37,7 @@ will in turn demand information about that crate, starting from the
   actual parsing.
 
 Although this vision is not fully realized, large sections of the
-compiler (for example, generating [MIR](./mir/)) currently work exactly like this.
+compiler (for example, generating [MIR](./mir/index.md)) currently work exactly like this.
 
 [^incr-comp-detail]: The ["Incremental Compilation in Detail](queries/incremental-compilation-in-detail.md) chapter gives a more
 in-depth description of what queries are and how they work.

src/tests/running.md

@@ -211,7 +211,7 @@ See [Compare modes](compiletest.md#compare-modes) for more details.
 
 Sometimes it's easier and faster to just run the test by hand.
 Most tests are just `rs` files, so after
-[creating a rustup toolchain](/building/how-to-build-and-run.html#creating-a-rustup-toolchain),
+[creating a rustup toolchain](../building/how-to-build-and-run.md#creating-a-rustup-toolchain),
 you can do something like:
 
 ```bash