Gather all links at the end of the file

CONTRIBUTING.md

@@ -17,10 +17,6 @@ Bug reports, feature requests and pull requests are all most welcome!
   Please report it using GitHub's [issue tracker].
   Select “feature request”.
 
-[discussions board]: https://github.com/tweag/cooked-validators/discussions
-[issue tracker]: https://github.com/tweag/cooked-validators/issues
-[documentation]: https://tweag.github.io/cooked-validators/
-
 ## Running and testing
 
 ### Environment
@@ -32,8 +28,6 @@ Our Nix integration provides everything one needs to contribute:
 
 - The environment `nix develop .#default` contains that plus everything needed for development, including [Haskell Language Server], [Ormolu], etc.
 
-[nix]: https://nixos.org/
-
 Alternatively, one can work on _Cooked Validators_ without Nix, using only GHC 8.10.7 and Cabal.
 
 ### Running and testing
@@ -56,8 +50,6 @@ All 16 tests passed (12.32s)
 
 Our continuous integration checks all of this automatically.
 
-[haskell language server]: https://github.com/haskell/haskell-language-server
-
 ## How to submit changes
 
 Changes are submitted by means of [pull requests].
@@ -71,8 +63,6 @@ The process of submitting pull requests has several goals:
 
 - Enable a sustainable system for _Cooked Validators_'s maintainers to review contributions.
 
-[pull requests]: https://github.com/tweag/cooked-validators/pulls
-
 Please follow these steps to have your contribution considered by the maintainers:
 
 - Follow all instructions in the template.
@@ -86,8 +76,6 @@ Please follow these steps to have your contribution considered by the maintainer
 
 While the prerequisites above must be satisfied prior to having your pull request reviewed, the reviewer/s may ask you to complete additional design work, tests, or other changes before your pull request can be ultimately accepted.
 
-[status checks]: https://help.github.com/articles/about-status-checks/
-
 ## How to report a bug
 
 Bugs are tracked using GitHub's [issue tracker].
@@ -157,9 +145,6 @@ Fill in the template, including the steps that you imagine you would take if the
 
 - Document all your functions using [Haddock]'s syntax.
 
-[ormolu]: https://github.com/tweag/ormolu
-[haddock]: https://haskell-haddock.readthedocs.io/en/latest/
-
 ### Nix style guide
 
 - All Nix code is formatted with [nixfmt].
@@ -168,9 +153,20 @@ Fill in the template, including the steps that you imagine you would take if the
 
 - Provide documentation explaining any bit of code that is not standard.
 
-[nixfmt]: https://github.com/serokell/nixfmt
-
 ### CI and pre-commit hooks
 
 Most of those coding conventions are enforced automatically by our continuous integration.
 The Nix environment provides pre-commit hooks that check those coding conventions in the exact same way the CI does.
+
+[discussions board]: https://github.com/tweag/cooked-validators/discussions
+[issue tracker]: https://github.com/tweag/cooked-validators/issues
+[pull requests]: https://github.com/tweag/cooked-validators/pulls
+[documentation]: https://tweag.github.io/cooked-validators/
+
+[status checks]: https://help.github.com/articles/about-status-checks/
+
+[haskell language server]: https://github.com/haskell/haskell-language-server
+[nix]: https://nixos.org/
+[ormolu]: https://github.com/tweag/ormolu
+[haddock]: https://haskell-haddock.readthedocs.io/en/latest/
+[nixfmt]: https://github.com/serokell/nixfmt