doc: update URLs

Some are now redirecting, some are outdated, i.e qt5.

CONTRIBUTING.md

@@ -80,7 +80,7 @@ facilitates social contribution, easy testing and peer review.
 
 To contribute a patch, the workflow is as follows:
 
-  1. Fork repository ([only for the first time](https://docs.github.com/en/get-started/quickstart/fork-a-repo))
+  1. Fork repository ([only for the first time](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/fork-a-repo))
   1. Create topic branch
   1. Commit patches
 
@@ -121,7 +121,7 @@ Commit messages should be verbose by default consisting of a short subject line
 paragraph(s), unless the title alone is self-explanatory (like "Correct typo
 in init.cpp") in which case a single title line is sufficient. Commit messages should be
 helpful to people reading your code in the future, so explain the reasoning for
-your decisions. Further explanation [here](https://chris.beams.io/posts/git-commit/).
+your decisions. Further explanation [here](https://cbea.ms/git-commit/).
 
 If a particular commit references another issue, please add the reference. For
 example: `refs #1234` or `fixes #4321`. Using the `fixes` or `closes` keywords
@@ -182,7 +182,7 @@ for more information on helping with translations.
 ### Work in Progress Changes and Requests for Comments
 
 If a pull request is not to be considered for merging (yet), please
-prefix the title with [WIP] or use [Tasks Lists](https://docs.github.com/en/github/writing-on-github/getting-started-with-writing-and-formatting-on-github/basic-writing-and-formatting-syntax#task-lists)
+prefix the title with [WIP] or use [Tasks Lists](https://docs.github.com/en/get-started/writing-on-github/getting-started-with-writing-and-formatting-on-github/basic-writing-and-formatting-syntax#task-lists)
 in the body of the pull request to indicate tasks are pending.
 
 ### Address Feedback
@@ -401,7 +401,7 @@ about:
   - It may be because your code is too complex for all but a few people, and those people
     may not have realized your pull request even exists. A great way to find people who
     are qualified and care about the code you are touching is the
-    [Git Blame feature](https://docs.github.com/en/github/managing-files-in-a-repository/managing-files-on-github/tracking-changes-in-a-file). Simply
+    [Git Blame feature](https://docs.github.com/en/repositories/working-with-files/using-files/viewing-and-understanding-files). Simply
     look up who last modified the code you are changing and see if you can find
     them and give them a nudge. Don't be incessant about the nudging, though.
   - Finally, if all else fails, ask on IRC or elsewhere for someone to give your pull request