docs: Links to RELEASE_NOTES.md and Source in CONTRIBUTING.md (#…

…5076)

Co-authored-by: Fabio Madge <fabio@madge.me>

CONTRIBUTING.md

@@ -30,7 +30,7 @@ If you want to propose code changes for the Dafny project, please note:
 - To propose code changes, use the standard Github multi-user project process, which is described for Dafny on the [wiki](https://github.com/dafny-lang/dafny/wiki/Setting-up-a-development-copy-of-Dafny).
 
 If your change is user-visible, then part of the PR should be corresponding changes to the
-[`RELEASE_NOTES.md`](../RELEASE_NOTES.md) file and to the 
+[`RELEASE_NOTES.md`](./RELEASE_NOTES.md) file (by following [this](./docs/dev/README.md)) and to the 
 [Dafny Reference Manual](./docs/DafnyRef).
 
 Any PR should have tests that check whether the bug-fix fixes the problem addressed or that the new functionality 
@@ -40,7 +40,7 @@ is properly working.
 
  Each `.dfy` file in this directory is a test, with a [`lit`](https://llvm.org/docs/CommandGuide/lit.html) header describing how to run it and a `.expect` file indicating the expected output. See [this README.md file](Source/IntegrationTests/TestFiles/LitTests/LitTest/README.md) for more info on running Dafny' integration tests.
 
- - Dafny's unit tests are in various `*.Test` directories in [`Source`](../Source).
+ - Dafny's unit tests are in various `*.Test` directories in [`Source`](./Source).
 
  Our CI is configured to run all tests when you create a PR. To run tests locally, use `dotnet test Source/Dafny.sln` (but note that running the tests for our compiler backends requires installing lots of additional software).