SubmittingPatches: replace discussion of Travis with GitHub Actions

Replace the discussion of Travis CI added in
0e5d028a7a (Documentation: add setup instructions for Travis CI,
2016-05-02) with something that covers the GitHub Actions added in
889cacb689 (ci: configure GitHub Actions for CI/PR, 2020-04-11).

The setup is trivial compared to using Travis, and it even works on
Windows (that "hopefully soon" comment was probably out-of-date on
Travis as well).

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/SubmittingPatches

@@ -74,10 +74,9 @@ the feature triggers the new behavior when it should, and to show the
 feature does not trigger when it shouldn't.  After any code change, make
 sure that the entire test suite passes.
 
-If you have an account at GitHub (and you can get one for free to work
-on open source projects), you can use their Travis CI integration to
-test your changes on Linux, Mac (and hopefully soon Windows).  See
-GitHub-Travis CI hints section for details.
+Pushing to a fork of https://github.com/git/git will use their CI
+integration to test your changes on Linux, Mac and Windows. See the
+<<GHCI,GitHub CI>> section for details.
 
 Do not forget to update the documentation to describe the updated
 behavior and make sure that the resulting documentation set formats
@@ -449,13 +448,12 @@ their trees themselves.
   entitled "What's cooking in git.git" and "What's in git.git" giving
   the status of various proposed changes.
 
-[[travis]]
-== GitHub-Travis CI hints
+== GitHub CI[[GHCI]]]
 
-With an account at GitHub (you can get one for free to work on open
-source projects), you can use Travis CI to test your changes on Linux,
-Mac (and hopefully soon Windows).  You can find a successful example
-test build here: https://travis-ci.org/git/git/builds/120473209
+With an account at GitHub, you can use GitHub CI to test your changes
+on Linux, Mac and Windows. See
+https://github.com/git/git/actions/workflows/main.yml for examples of
+recent CI runs.
 
 Follow these steps for the initial setup:
 
@@ -463,31 +461,18 @@ Follow these steps for the initial setup:
   You can find detailed instructions how to fork here:
   https://help.github.com/articles/fork-a-repo/
 
-. Open the Travis CI website: https://travis-ci.org
-
-. Press the "Sign in with GitHub" button.
-
-. Grant Travis CI permissions to access your GitHub account.
-  You can find more information about the required permissions here:
-  https://docs.travis-ci.com/user/github-oauth-scopes
-
-. Open your Travis CI profile page: https://travis-ci.org/profile
-
-. Enable Travis CI builds for your Git fork.
-
-After the initial setup, Travis CI will run whenever you push new changes
+After the initial setup, CI will run whenever you push new changes
 to your fork of Git on GitHub.  You can monitor the test state of all your
-branches here: https://travis-ci.org/__<Your GitHub handle>__/git/branches
+branches here: https://github.com/<Your GitHub handle>/git/actions/workflows/main.yml
 
 If a branch did not pass all test cases then it is marked with a red
-cross.  In that case you can click on the failing Travis CI job and
-scroll all the way down in the log.  Find the line "<-- Click here to see
-detailed test output!" and click on the triangle next to the log line
-number to expand the detailed test output.  Here is such a failing
-example: https://travis-ci.org/git/git/jobs/122676187
+cross. In that case you can click on the failing job and navigate to
+"ci/run-build-and-tests.sh" and/or "ci/print-test-failures.sh". You
+can also download "Artifacts" which are tarred (or zipped) archives
+with test data relevant for debugging.
 
-Fix the problem and push your fix to your Git fork.  This will trigger
-a new Travis CI build to ensure all tests pass.
+Then fix the problem and push your fix to your GitHub fork. This will
+trigger a new CI build to ensure all tests pass.
 
 [[mua]]
 == MUA specific hints